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▸ Geography is the science that studies the lands, the features, the inhabitants and the phenomena of the Earth. ▸ The word geography adopted in the 2nd century BC by the Greek Scholar Eratosthenes. Some Contributors to Geography ▸ Eratosthenes was the first person to calculate the circumference of the Earth and also calculate the tilt of the Earth's axis. ▸ Anaximander created the first map of world. ▸ Ainville made the first map of India. ▸ Ptolemy first presented India on the world map. ▸ Anthropogeography was written by Friedrich Ratzel.
Geography is divided into two main branches i.e. physical geography and human geography. Human Geography Human geography is a branch of the geography that studies the world, its people, communities and cultures with an emphasis on relations of land across space and place. The fields of human geography are as follow: ▸ Cultural geography ▸ Development geography ▸ Economic geography ▸ Health geography ▸ Historical geography ▸ Political geography ▸ Population geography ▸ Settlement geography Physical Geography Physical geography deals with the physical environment and the various process that bring about changes in the physical environment on the Earth surface. The fields of physical geography are as follow: ▸ Geomorphology It is the scientific study of landforms and processes that shape them. ▸ Hydrology It is the study of the movement, distribution and quality of water on Earth, including the hydrological cycle, water resources and environmental watershed sustainability. ▸ Climatology It is the study of climate, scientifically defined as weather conditions averaged over a period of time. ▸ Pedology It is the study of soils in their natural environment. ▸ Glaciology It is the study of glaciers and ice sheets. ▸ Biogeography It is the study of relationships of organisms with their environment.
▸ The study of universe is known as Cosmology. ▸ The universe is commonly defined as the totality of everything that exists including all physical matter and energy, the planets, stars, galaxies and the contents of intergalactic space. ▸ The universe comprises of billions of galaxies. The galaxies are made up of millions of stars held together by the force of gravity and these stars account for most of the masses of the galaxy. Andromeda is our nearest galaxy. ▸ Our own galaxy is called the Milky Way (or the Akash Ganga) and it contains about 300 billion stars and one of these is our Sun. Planets and other objects revolve around the Sun and make up the solar system with the Sun at the centre. ▸ In AD 140, Ptolemy propounded the theory that the Earth was the centre of the universe and the Sun and the other heavenly bodies revolved around it. ▸ In 1543, Copernicus said that the Sun is the centre of universe and not the Earth. ▸ Kepler supported Copernicus but said that the Sun is the centre of solar system and not the universe. ▸ In 1924, Edwin Hubble first demonstrated existence of galaxies beyond Milky Way. ▸ Structurally, the galaxies are found in three forms (i) Spiral have a central nucleus with great spiral arms. Milky Way and Andromeda are the examples. (ii) Elliptical without spiral arms. (iii) Irregular with no shape.
The three main theories put forward to explain the origin and evolution of the universe are (i) Big Bang Theory (Proposed by Georges Lemaitre) Big Bang was an explosion that occurred 13.8 billion years ago, leading to the formation of galaxies of stars and other heavenly bodies. (ii) Steady State Theory Bondi, Gold and Fred Hoyle developed this theory and states that although the universe is expanding, it nevertheless does not change its appearance over time, it has no beginning and no end. (iii) The Pulsating Theory According to this theory, the universe is supposed to be expanding and contracting alternately i.e. pulsating. At present, the universe is expanding. NASA has launched the Cosmic Background Explorer (COBE) and the Wilkinson Microwave Anistropy Probe (WMAP) missions to study the radiation present in the universe.
▸ Stars are heavenly bodies made up of hot burning gases, thus shining by their own light. ▸ If the star is bigger than the Sun but not more than twice as big, it will turn into a Neutron star or Pulsar. They are formed due to novae or super novae explosion. ▸ A star's colour indicates the temperature of its surface. Blue colour denotes maximum temperature, then comes yellow, then red etc. Evolutionary Stages of a Star 1. Proto Star It is the stage, where the heliumcore become increasingly heavy, accompanied with expanding outer layers. 2. Red Giant This stage results into the swelling and reddening of the outer regions of the star. Such stars of gigantic dimension is called Red Star. 3. White Dwarf If the mass of the star is relatively small like that of our Sun, the gases that reach the outer layer are expelled. As these expelled gases cool and contract, the star becomes a White Dwarf. Stars: Quick Digest ▸ Brightest star outside solar system is Sirius, also called as Dog Star. ▸ Closest star to our solar system is Proxima Centauri (4.2 light years away). Followed by Alpha Centauri (4.3 light years away) and Barnard's Star (5.9 light years away). Concept of BlackHole and Chandrashekhar Limit ▸ There is an upper limit to the mass of stars, above which two things are possible 1. Explosion of the star to form neutron stars called Pulsar. 2. Collapse and compaction of the star to form Black Holes. ▸ Therefore, the black holes are formed due to collapse and compaction under gravity, at the end of the life cycle. ▸ A renowned Indian Physicist Chandrashekhar had predicted an upper limit to the mass of stars, which is called as Chandrashekhar limit. It is 1.44 times the mass of the Sun. ▸ Some of the units used for the calculation of these distances are as follows: Units of Distance
Light year
It is the distance that light can travel in 1 year. Our solar system is less than 1 light day across.
Astronomical unit
It is the average distance between the Sun and the Earth. 1 light year = (almost) 60000 Aus
Parsec
It is the distance from the Earth to a star that has parallax of 1 arc second. The actual length is about 3.262 light years.
▸ The solar system comprises the Sun, 8 planets, their Moon and other non-stellar objects, which are believed to have been developed from the condensation of gases and other lesser bodies. ▸ The Sun is at the centre of the solar system and all the planets revolve around it in elliptical orbit. It is the nearest star to the Earth. ▸ The size of solar system has been estimated to be about 105 AU.
Our Solar System consists of ▸ the Sun, Eight planets (excluding Pluto) and their respective satellites. ▸ interstellar debris such as asteroids, meteoroids, comets. The electrically charged gases, called Plasma. ▸ interplanetary dust particles. ▸ the components of solar system other than planets dwarf planets and satellites are called as Small Solar System Bodies (SSSB).
Various theories were given to explain the Origin of the Solar System.
Gaseous Hypothesis
Kant
Nebular Hypothesis
Laplace
Planetesimal Hypothesis
Chamberline and Moulton
Tidal Hypothesis
Sir James Jeans and Harold Jeffreys
Binary Star Hypothesis
HN Russell
Supernova Hypothesis
F Hoyle
Interstellar Dust Hypothesis
Otto Schmidt
Electromagnetic Hypothesis
H Alfven
▸ The Sun accounts for more than 99 per cent of the mass of the Solar System and due to this, the Sun exerts immense gravitational pull to keep the planets rotating around it in definite elliptical orbit. ▸ The Sun is the major source of energy of the solar system. The energy is provided by the nuclear fusion reaction, that converts hydrogen into helium in the core of the Sun. ▸ The glowing surface of the Sun that we see is called as Photosphere. Above the photosphere is the red coloured Chromospheres and beyond it is the magnificent corona, which is visible during eclipses. ▸ Hydrogen and helium are the main gases present in the Sun. ▸ It has a surface temperature of about 6000°C. ▸ It takes 224 million years to complete one circle (revolution) around the galactic circle called cosmic year. ▸ The Sun is 1300000 times bigger than the Earth in terms of volume. ▸ Superimposed on Sun's white light are hundred of dark lines called Fraunhofer lines. Each line indicates some elements present in the Solar System.
Specifics of the Sun
Average distance from the Earth
149598900 km
Diametre
1391980 km
Temperature of the core
15000000°C
Rotation speed
25.38 days (with respect to equator); 33 days (with respect to poles)
Time taken by sunlight to reach the Earth
8 min and 16.6 sec
Concepts Associated with the Sun ▸ Solar Winds The Sun is continuously emitting streams of photon in all directions either as spiral streams called Solar Wind or bouts of incandescent material called Solar Flares. Solar flares being hot ionised gases pose danger to satellite communication. ▸ Aurora The constituent particles of the solar wind are trapped by the Earth's magnetic field and enter the Earth's upper atmosphere as Aurora. It is described as Aurora Borealis in the Northern hemisphere and Aurora Australis in Southern hemisphere. ▸ Plages and Sunspots The surface of the Sun is continuously changing. Bright spots are called Plages and dark spots are called Sunspots. The Sunspots are cold and dark regions on the Sun's surface with a periodicity of 11 years. These spots greatly influence the global climate.
▸ Planets are opaque bodies, which continuously revolve around and are lighted by the Sun. There are eight planets in the solar system. ▸ The sequence of planets according to their size (in descending order) is Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars and Mercury. ▸ The sequence of planets according to their distance from the Sun is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Classification of Planets 1. Inner Planets Include Mercury, Venus, Earth and Mars. 2. Outer Planets Include Jupiter, Saturn, Uranus and Neptune.
They are called as Terrestrial or Rock planets. They are nearer to the Sun.
They are called as Jovian or Gaseous planets. They are far away from the Sun.
They have very few natural satellites (or moons) or no satellites.
They have a large number of natural satellites (or moons).
They have a core of molten metals.
They have ring system around the Sun.
They move faster and have a shorter period of revolution.
They move rather slowly and have a longer period of revolution.
Specifics of the Planets
Hottest Planet
Venus
Densest Planet
Earth
Fastest Rotation in Solar System
Jupiter
Morning Star
Nearest Planet to Earth
Nearest Planet to Sun
Mercury
Red Planet
Mars
Biggest Satellite
Ganymede
Blue Planet
Green Planet
Uranus
Brightest Planet
Slowest Revolution in Solar System
Neptune
Slowest Rotation in Solar System
Smallest Planet
Smallest Satellite
Phobos
Earth's Twin
Only Satellite with an Atmosphere Like Earth
Titan
A Comparative Study of the Planets of the Solar System
Planets
Special Characteristics
Rotation and Revolution Time
Important Physical Properties
Satellite Systems
Smallest and the innermost planet. It has no atmosphere. It has a cratered surface, much like the Moon.
Rotation : 58.65 days Revolution: 88 days (Fastest Revolution in the Solar System).
It has the maximum diurnal range of temperature.
No satellite
Also called as the veiled planet. known as (Evening and Morning star) as it is seen in the East in morning and in the West in the evening. It is the brightest object in solar system because of almost 70% albedo. It contains 90 to 95%CO2. The night and day temperature almost the same.
It has the slowest rotational speed. It has almost equal rotation and revolution. Rotation (Clockwise) 257 days and Revolution: 224.7 days.
Rotates from East to West unlike the other planets. It is the hottest planet.
The Earth is neither too hot nor too cold.It is called as the Blue Planet due to the presence of water.
Rotation :24 hours; Revolution : 365 days and 6 hours.
It is the densest of all and is unique for the presence of higher forms of life.
Moon is the only natural satellite.
Called as Red Planet. It has a thin atmosphere comprising of nitrogen and argon.
Rotation 24.6 hour. (almost equal to Earth) Revolution: 687 days.
It is marked by dormant volcanoes. Nix Olympia is the highest mountain, which is three times higher than the Mount Everest.
Two satellites : Phobos and Deimos .
It is the largest planet in the solar system with a mass 2.5 times greater than the combined mass of all the remaining planets, satellites and asteroids put together. In contains hydrogen, helium, methane and ammonia. A great red spot is detected on it.
Fastest rotational velocity (9.8 hrs)
It is too massive to solidify as a planet but not massive enough to develop nuclear fusion and become a star. It gives off more energy than it receives from the Sun, because of the heat inside.
It has 67 satellites. Some of the prominent satellites are: Europa, Callisto and Ganymede. These are called as Galileon Moons.
It is unique as its axis of rotation is inclined at 98° to its orbital plane.
Unlike the others, which spin on their axis, Uranus actually rolls, apparently from North to South.
Surrounded by a system of 9 faint rings.
It has 27 satellites .The prominent are Miranda Ariel etc.
It is a penultimate planet, has a dynamic atmosphere, which contains an the Earth sized blemish called the Great Dark Spot that is reminiscent of Jupiter's Great Red Spot .
Rotation 15.7 days and Revolution 165 years.
It has 5 faint rings .It appears as Greenish Star.
It has 14 satellites. The prominent are Triton and Nereid.
▸ Pluto was discovered by Clyde Tombaugh in 1930. ▸ The redefinition of planet by the International Astronomical Union (IAU) on 24th August, 2006 states that, in the solar system, a planet is a celestial body that ▸ it is in orbit around the Sun. ▸ it has sufficient mass so that it assumes a hydrostatic equilibrium (nearly round) shape. ▸ it has cleared the neighbourhood around its orbit. ▸ A non-satellite body fulfilling the first two rule is classified as a Dwarf planet. So, Pluto is considered as Dwarf planet.
The study of Moon is called Selenology. Specifics of the Moon
Rotation Period
day, 7 h, 43 min and 11.47s
Atmosphere
Absent
Part of Moon not visible from Earth
41%
Maximum distance from Earth (Apogee)
km
Minimum distance from Earth (Perigee)
Circumference
Diameter
Mass (with respect to Earth)
: 8.1
Ratio of Gravitational Pull of Moon and Earth
: 6
Highest Mountain
ft (Leibnitz Mountain)
Time Taken by Moonlight to Reach Earth
1.3 s
kmph
Speed of Revolution around Earth
Revolution Period around Earth
days, 7 h, 43 min and 11.47s
▸ Moon is also known as the fossil planet. ▸ The Moon is the only natural satellite of the Earth. ▸ The Moon has no atmosphere, no twilight and no sound. ▸ The size of the Moon is one-fourth (1/4th) the size of the Earth. ▸ Gravitational pull of the Moon is one-sixth (1/6th) that of the Earth. ▸ Silicon, iron, magnesium etc elements are found mainly on the Moon's surface.
Asteroids, Meteoroids, Comets
Various Aspects
Asteroids or Planetoids
Constitutents and Genesis
Composed of rocks, dust and metal. They cannot retain their atmosphere due to small size.
Comets may originate in a huge cloud called the Oort cloud that is thought to surround the solar system. It is composed of frozen gases and dust.
Meteoroids are small fragments of rocks and metal. Under the Earth's gravitational field, they become white hot through friction as they fall through the atmosphere and are seen as the Meteors or Shooting stars.
Shape and Size
No definite shape, rather same as of Planetoids or small planet.
Comets have a head and tail, where the tail always points away from the Sun because of the solar wind and the radiation pressure.
No definite shape.
Orbit
They orbit the Sun in the asteroid belt, which lies between the orbits of Mars and Jupiter.
They have an extremely eccentric orbit but with definite periodicity.
Meteoroids travel through space. Meteors are scattered in the interplanetary space of the solar system.
Iron—35% 2. Oxygen—30% 3. Silicon—15% 4. Magnesium—13% 5. Nickel—2.4% 6. Sulphur—1.9% 7. Calcium—1.1% 8. Aluminium—1.4% 9. Others—0.5%
▸ Earth is the third planet from the Sun and the densest and the fifth-largest of the eight planets in the solar system.It is also the largest of the solar system's four terrestrial planets. Earth is also called as Blue Planet. ▸ The age of the Earth is estimated at about 4.6 billion years. The history of the Earth is studied in terms of geological eras, periods and epochs. The whole history is divided into three Eras- Palaeozoic, Mesozoic and Cenozoic. Geological History of the Earth
Modern man
Pleistocene Epoch
2 million
Homo Sapiens
Tertiary Period Pliocene Epoch
5 million
Early human ancestor
Miocene Epoch
24 million
Flowering plants and trees
Oligocene Epoch
38 million
Early horses, cats, dogs, camel
Eocene Epoch
55 million
Rabbits, hare
Palaeocene Epoch
63 million
Small mammals : Rats, mice
Mesozoic Era Cretaceous Period
138 million
Extinction of dinosaurs
Jurassic Period
205 million
Age of dinosaurs
Triassic Period
240 million
Frogs and turtles
Palaeozoic Era Permian Period
290 million
Reptile dominate, Replace amphibians
Lower Carboniferous Period
330 million
1st Reptiles
Upper Carboniferous Period
360 million
Fish
Devonian Period
410 million
Silurian Period
435 million
Corals
Ordovician Period
500 million
Graptolites
Cambrian Period
570 million
Trilobites
Pre-Cambrian Time
4.5 billion
Bacteria
Specifics of the Earth
Mass
5.9 × 1024 kg
Volume
1083 × 1012 Km3
Mean Density
5.513 g/cm3
Shape
An oblate spheroid or a geoid
Radius of Earth
6400 km
Total surface area
509700000 sq km
Land area (29%)
148400000 sq km
Water area (71%)
361300000 sq km
Rotation time
23 hours 56 minute and 4.09 seconds
Revolution time
365 days, 5 hours, 48 minutes and 45.51 seconds
Orbit speed about the Sun
29.8 km/second
Mean surface temperature
14°C
Highest temperature recorded
58°C Al-Aziziyah
Mean Distance from the Sun
149598500 km
Inclination of polar axis from orbital plane
23° 26 min and 59 s
Deepest ocean point
11034 m, Mariana Trench (Pacific Oceans)
Time coordinate of Earth
Longitude
Temperature coordinate of Earth
Latitudes
▸ The Earth moves in space in two distinct ways:Rotation and Revolution. (i) It rotates on its own axis from West to East once in every 24 hours. It causes day and night. (ii) It revolves around the Sun in an orbit once in every 365¼ days. It causes the seasons and the year.
▸ Spins on its imaginary axis from West to East in 23 hours, 56 minutes and 40.91 seconds. ▸ The rotational speed at equator is maximum (1667 km/hr) and then decreases towards the poles, where it is zero. ▸ The days and the nights are equal at the equator. The rotation of the Earth has the following implications such as: ▸ Causation of day and night. ▸ Change in the direction of winds and ocean currents. ▸ Rise and fall of tides everyday. ▸ A difference of one hour between the two meridians which are 15° apart.
▸ It is the Earth's motion in elliptical orbit around the Sun. It takes 365 days, 5 hours, 48 minutes and 45.51 seconds. It leads to one extra day in every fourth year. The revolution of the Earth results in ▸ changes of season. ▸ variation of the length of the days and nights at different times of the year. Shifting of the wind belts. Below figure shows the revolution of the Earth and its effects on seasons and the variations of lengths of day and night.
Major Difference Between Rotation and Revolution of Earth
Rotation
Revolution
Turning around the Earth on its own axis.
Movement of the Earth around the Sun.
Earth takes 24 hours to complete one rotation.
The Earth takes 365.25 days to complete revolution.
Rotation causes day and night.
Revolution along with inclination of the Earth on its axis causes change in seasons.
Earth's Position wrt Moon Apogee: The period of the farthest distance between the Moon and the Earth is called Apogee. It is about 407000 km. Perigee: The period of the nearest distance between the Moon and the Earth is called Perigee. It is about 364000 km. Earth's Position wrt Sun Perihelion: The period of the nearest distance between the Earth and the Sun is Perihelion. It happens on 3rd January and the distance is 147 million km. Aphelion: The period of the farthest distance between the Earth and the Sun is Aphelion. It happens on 4th July and the distance is 152 million km.
▸ The axis of the Earth is inclined to the plane of ecliptic (the plane, in which the Earth orbits round the Sun) at an angle of 66½° giving rise to different seasons and varying lengths of day and night. ▸ If the axis were perpendicular to this plane, all parts of the globe would have equal days and nights at all times of the year. Sun 22nd December 21st June Equator NP SP Summer in N hemisphere Winter in S hemisphereNP SP Autumn in S hemisphere NP SP Winter in N hemisphere Equator NP SP 23rd September 21st March Summer in S hemisphere Revolution of the Earth ▸ The Earth is tilted about 23.5° from a line perpendicular to ecliptic plane.
▸ These are the days, when days and nights are equal. Under this situation, the Sun is vertically overhead at the equator. It happens on two days of the year i.e. 21st March and 23rd September. ▸ 21st March: Vernal Equinox. ▸ 23rd September: Autumnal Equinox.
▸ After the March equinox, the Sun appears to move Northward and is vertically overhead at the Tropic of Cancer on 21st June. This is known as Summer Solstice. ▸ On 21st June, the Northern hemisphere will have its longest day and shortest night. The Southern hemisphere will have shortest day and longest night. Winter Solstice ▸ On 22nd December, the Sun is overhead at the Tropic of Capricorn. This is the winter solstice, when the Southern hemisphere will have its longest day and shortest night. A summary of daylight hours in the Northern and Southern hemisphere is as follows: Winter Solstice
Longest day in the Northern
21st June
Shortest day in the Northern hemisphere
22nd December
Equal day and night in the Northern hemisphere
21st March and 23rd September
Longest day in the Southern hemisphere
Shortest day in the Southern hemisphere
Equal day and night in the Southern hemisphere
▸ They are the periods into which the year can be divided as a result of the climatic conditions, mainly due to the changes in duration and intensity of solar radiation. ▸ There are four seasons such as:
Spring
Summer
Autumn
Winter
When the Sun is directly overhead the equator. (21st March)
When the Sun is directly overhead the Tropic of Cancer -the North temperate zone experiences summer. (21st June)
When the Sun returns to the equator and the North temperate zone experiences the season of autumn. (23rd September)
The Sun is at the Tropic of Capricorn and the North temperate zone experiences winter. (22nd December)
▸ Latitude is the angular distance of a point on the Earth surface from the centre of the Earth, measured in degree. These lines are called parallels of latitude and on the globe they are circles. The circumference of the circles decreases from equator to pole and at the pole it converses to a point. ▸ The distance between any two parallels of latitude is always equal. One degree latitude = Approx 111 km. The most important lines of latitudes are Equator (0°), the Tropic of Cancer (23½°N), the Tropic of Capricorn (23½°S), the Arctic Circle (66½°N) and the Antarctic Circle (66½°S).
▸ Longitude is the angular distance of a point on the Earth surface along the equator, East or West from the Prime meridian. On the globe, they form semi-circles from pole to pole passing through the equator.
▸ Prime meridian is the semi-circle from pole to pole, from which all the other meridians radiate Eastwards and Westwards up to 180°. In 1884, it has been decided that the zero meridian is one that passes through the Royal Astronomical Observatory at Greenwich near London. 180° meridian (International Date Line) is exactly opposite to the prime meridian. Such points are called antipodal points. Universal Time (Standard time) and Time Zones ▸ To avoid confusion about having many local times within one country, a particular meridian is chosen for the whole country, whose time is known as standard time. ▸ The Indian Government has accepted the meridian of 82.5 degree East for standard time, which is 5 hrs 30 mins ahead of the Greenwich Mean Time. ▸ The Earth is divided in 24 longitudinal zones, each being 15 degree or 1 hour apart in time (360 degree = 24 hours, 360/24 = 15 degree in 1 hour) or 1 degree in 4 minute are called Standard Time Zones. ▸ Larger countries such as USA, Russia and Canada, which have greater East-West stretch have to adopt several time zones for practical purposes. ▸ Russia has asmany as 11 time zones. ▸ Both USA and Canada have five time zones, viz, the Atlantic, Eastern, Central, Mountain and Pacific time zones. ▸ A simple memory aid for time is East-Gain-Add (EGA) and West- Lose-Subtract (WLS).
▸ It is the 180 degree meridian running over the Pacific Ocean, deviating at Aleutian Island, Fiji, Samoa and Gilbert Island. ▸ This is the International Date Line, where the date changes by exactly one day, when it is crossed. ▸ Samoa and Tokelau shifted his position back to West of the date line on 30th December, 2011.
▸ An eclipse occurs when the Sun, the Moon and the Earth are in a straight line. There are two types of eclipses-Solar and Lunar eclipse. ▸ Generally, a total of seven eclipse including solar and lunar eclipses, take place in a year. Latitude and Longitude on the Earth Lunar Eclipse ▸ It is the situation, when the Earth comes between Sun and Moon. ▸ It occurs only on a full Moon day. But, it does not occur on every full Moon day because the Moon is so small and the plane of its orbit is tilted about 5 degree with respect to the Earth's orbital plan.
Solar Eclipse ▸ It is the situation, when the Moon comes between Sun and Earth. ▸ It occurs only on a new Moon day. But, it does not occur on every new Moon day because of the inclination of the Moon’s orbital plan.
The interior of Earth is divided into three parts (i) Crust (ii)Mantle (iii) Core
▸ The crust is the outermost and the thinnest layer of the Earth. This layer has the least density and its thickness varies about 8 to 40 km. Mohorovicic Discontinuity or Moho, marks the lower limit of the crust and this discontinuity is identified on the basis of rock density. ▸ Thickness of the crust is more in the continents and lesser in the oceans while density of continental crust is lower than oceans. ▸ The rocks forming the crust of the Earth are rich in lighter minerals like silica and aluminium. Hence, this layer is also called as Sial (silica and aluminium). The average density of this layer is 2.7 gm/cm3. ▸ Due to presence of minerals like silica and magnesium in the rocks forming this layer of the Earth known as Sima (silica and magnesium). ▸ Sial and Sima together form Earth crust.
▸ This layer is the intermediate layer of the Earth in terms of both its location and density. ▸ It is about 2900 km in thickness, composed of minerals in a semisolid state. ▸ It is divided into further two layer upper mantle and lower mantle. The upper part of the mantle is called the Asthenosphere, which is about 250 km thick. ▸ The average density of this layer is about 5.68 gm/cm3. ▸ The transitional zone separating the mantle from the core is called the Gutenberg Discontinuity.
▸ The core is the innermost layer of the Earth and occupies its centre. It is about 3500 km in radius. ▸ The core is further divided into two layers : outer core and inner core. ▸ The outer part of the core is believed to have the properties of a liquid and the innermost part of the core (about 1255 km in radius) may be called solid or crystalline. ▸ This layer is also known as Nife (nickel and iron), because this layer contain large concentration of iron and nickel. ▸ Temperature of the core is between 2200°C and 2750° C. ▸ Density of this part of the Earth is 13.6 gm/cm3 and is many times greater than the average density of the Earth (5.53 gm/cm c3).
Discontinuities The various layers are separated by discontinuities, which are evident in seismic data. ▸ Conroad discontinuity lies between upper crust and lower crust. ▸ Mohorovicic discontinuity between crust and mantle. ▸ Repetti discontinuity lies between upper mantle and lower mantle. ▸ Gutenberg discontinuity between core and mantle. Here, the Earth's density as well as velocity of 'P' waves increases. ▸ Lehmann discontinuity divides upper core and lower core. Composition of the Earth's Crust
Elements
Percentage(%)
Oxygen
46
Calcium
Silicon
Sodium
2.8
Potassium
2.6
Iron
Magnesium
1.5
▸ This theory is given by Alfred Wegener, in 1915, to explain the origin and evolution of the continents and the oceans. According to this theory, about 250 million years ago, there was only one continent named Pangea means All Earth and it was surrounded by one mass of water body, named Panthalassa. ▸ The present shape of the continents and oceans is due to the break up of Pangaea. ▸ This breaking process started about 200 million years ago. ▸ The Northern rift cuts Pangea from East to West creating Laurasia in the North and Gondwanaland in South. A shallow sea called Tethys was situated between the Laurasia and the Gondwanaland.
▸ The concept of sea floor spreading was first formulated by Harry Hess in the year of 1960. ▸ According to this theory, the mid oceanic ridges were situated on the rising thermal convective current coming from mantle. ▸ The oceanic crust moves in opposite directions from mid oceanic ridges and thus there is continuous upwelling of new molten materials along the mid oceanic ridges. These molten masses cool down and solidify to form new crust.
▸ Plate tectonic is a scientific theory that describe the large-scale motions of Earth's lithosphere. ▸ The word tectonics comes from the Greek word meaning builder. ▸ The theory of Plate tectonics states that the lithosphere is divided into several rigid segments, which include both oceanic and continental crusts. These segments are called plates and they are moving on the asthenosphere, which is not a liquid, but a solid which flows under stress. ▸ About 20 such plates have been identified. There are seven major plates such as Eurasia, Antarctica, North America, South America, Pacific, African and Indian Plate. ▸ There are various intermediate sized plates such as China, Philippine, Arabian, Iran, Nazca, Cocos, Caribbean and Scotia Plates.
Depending upon the type of movement, plate margins are of three types : (i) Divergent Plate Margin (Constructive margins) (ii) Convergent Plate Margin (Destructive margins) (iii) Parallel Plate Margin (Conservative margin or Transform Boundary) ▸ Collision can occur between two oceanic plates, one oceanic and one continental plate or two continental plates.
▸ Appearance of the surface of the Earth keeps changing. ▸ These changes are produced under the influence of two type of forces. These are given below :
▸ The forces affecting the surface of the Earth from outside are called the external or exogenetic forces. ▸ Weathering and Erosion are the examples of external forces.
▸ The forces originating in the interior of the Earth are called the internal or the endogenetic forces. ▸ Volcanoes, Earthquakes and Landslide are the examples of internal forces. ▸ These forces are of two types: Sudden Endogenetic Forces ▸ Sudden endogenetic forces are the result of long period preparation deep within the Earth. ▸ But their cumulative effects on the Earth's surface are quick and sudden.
▸ Diastrophic forces include both vertical and horizontal movements which are caused due to forces deep within the Earth. These diastrophic forces operate very slowly and there effects become visible after thousands and millions of years. ▸ These forces termed as constructive forces effect larger areas of the globe and produce meso-level reliefs e.g. mountains, plateaus, plains, lakes, big faults etc. ▸ These diastrophic forces are further subdivided into two groups namely epirogenetic force and orogenetic force. Epirogenetic Force ▸ It causes upliftment and subsidence of continental masses through upward movements and are infact, vertical movements. These forces and resultant movements affect larger parts of the continents. These are further divided into two type: upward movement and downward movement. Orogenetic Force ▸ Orogenetic movement is caused due to endogenetic forces working in horizontal movement. Horizontal forces and movements are also called as tangential forces. Orogenetic or horizontal forces work in two ways, namely (i) in opposite direction and (ii) towards each other. ▸ When it operates in opposite direction, called tensional force. Tensional force create faulting cracking and fracture. Tensional forces are also called as divergent forces. ▸ The force, when operates face to face, is called compression force or convergent force. Compression force create folding and warping. Types of Plate Boundary
Divergent Plate Boundary
Convergent Plate Boundary
Transform Fault Boundary
When the plates move apart with the upwelling of material from the mantle, divergent plate boundary results.
A convergent plate boundary is one, where two plates collide, one plate bending downward and subducting below the other.
They are located, where plates slide past one another without the creation or destruction of crust.
Formation of the mid-oceanic ridges are the example of divergent plate margin.
Deep oceanic trench is formed adjacent to the zone of subduction. Fold mountains are the result of convergent plate boundary.
San Andreas fault along the West coast of Mexico is a famous transform fault.
▸ It refers to the vibration of the Earth's surface caused by the endogenetic forces of Earth. ▸ The magnitude or intensity of energy released by an earthquake is measured by the Richter Scale, whereas the damage caused is measured by modified Mercalli Intensity Scale. ▸ The place of origin of earthquake is called focus. The place on the ground surface, which is perpendicular to the focus or hypocentre is called Epicentre. ▸ Seismology is the special branch of geology that deals with the study of earthquake.
Earthquake waves are seismic waves that are created when energy builds up in rocks and they fracture. Earthquake waves are basically of two types : body wave and surface wave. BodyWaves They are generated due to the release of energy at the focus and move in all directions travelling through the body of the Earth. The body wave interact with the surface rocks and generate new set of waves called Surface Wave. There are two types of body waves Primary and Secondary wave. 1. PrimaryWave Primary Wave (P Waves) These are the waves of short wavelength and high frequency. They are longitudinal waves and can travel through solid, liquid and gases. 2. SecondaryWave Secondary Wave (S Waves) These are the waves of short wave length and high frequency. They are transverse waves, which travel through all solid particles.
They are the waves of long wavelength, confined to the skin of the Earth's crust. It causes most of the earthquake's structural damage.
The Indian plate is moving from South to North at the speed of 5 cm/year and the Eurasian Plate is static on its own position, so there is a collision between Indian Plate and Eurasian Plates. Due to this collision, the earthquakes occurs in the Himalayan regions of India. The collision also results in the increase of the height of Himalayas at the speed of 1 cm/year. ▸ The second most important earthquake zone is Parallel to Punjab and Rann of Kachchh. It occurs due to the movement between the transform boundaries of Eurasian and Indian Plates. ▸ Earthquakes occur in Assam, Arunachal Pradesh, Nagaland, Tripura, Manipur, Mizoram, Andaman and Nicobar Islands, Jammu and Kashmir, the North-Western region of Uttar Pradesh and the Northern region of Bihar etc. Distribution of Earthquakes Most of the world earthquake occur in ▸ the zones of young fold mountain ▸ the zones of folding and faulting ▸ the zone of junction of continental and oceanic margin ▸ the zone of active volcanoes ▸ along different plate boundaries The traditional zones of earthquakes ▸ Circum Pacific belt ▸ Mid Continental belt ▸ Mid Atlantic belt
▸ There are some specific area where earthquake waves do not occur or occur rarely such areas are termed as Shadow zone. ▸ It is located between 105° and 140° from epicentre.
▸ Volcanism includes all phenomena connected with the movement of heated material from the interior towards the surface of the Earth. ▸ A volcano is a vent or opening, through which heated materials consisting of gases, water, liquid lava, fragments of rocks are ejected from the highly heated interior to the surface of the Earth. ▸ Volcanic eruptions are closely associated with several integrated processes such as: ▸ Gradual increase in temperature with increasing depth, due to the heat generated by degeneration of radioactive elements inside the Earth. ▸ Origin of magma due to the lowering of the melting point caused by reduction in pressure of overlying rocks due to fractures caused by splitting of plates. ▸ Origin of gases and water vapour due to heating of water. ▸ Ascent of magma due to pressure from gases and vapour. ▸ Occurrence of volcanic eruption. Classification of Volcanoes On the Basis of Mode of Eruption Central Eruption or Explosive Type : Here the magma comes with great force through the small vent and spread to a distant position. e.g. Hawaiian type, Strombolian type, Pelean type, Vesuvious type, Volcanian type. Fissure Eruptionor Quiet Eruption: Large quantities of lava quietly flow up from fissures and spread out over the surrounding areas. Successive flow of lava results in the growth of lava plateau. e.g. Deccan Plateau. On the Basis of Periodicity of Eruptions
Active Volcano
Dormant Extinct Volcano Volcano
Volcano which errupt periodically e.g. Etna, Stromboli, Mayon
Volcano which become quiet after their eruption for some time e.g. Fujiyama, Krakatoa, Barren Island
They have no indication of future eruption
▸ Circum-Pacific Belt (Fire girdle of the Pacific or the fire ring of the Pacific). It extends across the Kamchatka Peninsula, Kurile Islands, the Islands of Japan, Philippines, New Guinea, New Zealand and the Soloman Islands. ▸ Highest Volacanic Peaks Cotopaxi (South America), Fujiyama (Japan), Valley of ten thousand smokes (Alaska).
▸ Mid-Continental Belt (Volcanic zones of convergent continental plate Margins). It includes volcanoes of Alpine mountain chain, the Mediterranean sea and the fault zone of Eastern Africa of Stromboli, Vesuvius, Etna, Kilimanjaro etc. ▸ Mid-Atlantic Belt, in which the volcanoes are fissure eruption type, e.g. Iceland, Canary Islands, Cape Verde, Azores etc.
It is the process of disintegration or decomposition of rocks in situ by natural agents. It is a static process. There are three types of weathering 1. Physical Weathering (or mechanical weathering) ▸ It involves rock disintegration without any change in the chemical constituents of the rocks. ▸ The factors responsible for physical weathering are temperature change, crystallisation of water into ice, the pressure release mechanism. 2. Chemical Weathering It involves the decomposition due to chemical changes. There are various chemical processes, which cause chemical weathering such as Solution, Oxidation, Carbonation, Hydration, Hydrolysis and Chelation. 3. BiologicalWeathering Plants and animals including man largely control it. It is divided into three types such as (i) Faunal weathering (ii)Floral weathering (iii) Anthropogenic weathering
It involves removal of rock material and then transpor- tation of it. Therefore, erosion is performed by mobile agents such as streams, winds, waves and underground water.
▸ The solid part of the Earth's crust are called rocks. ▸ The rocks are made up of two or more minerals. ▸ Minerals are obtained from rocks. A rock can be defined as an aggregate of minerals. Rocks are classified in three main types depending on the process of their formation (i) Igneous (ii)Sedimentary (iii) Metamorphic Important Volcanic Mountains
Names
Height (m)
Country
Location
Last Notified Eruption
Ojos del Salado
7084
Argentina-Chile
Andes
1981
Guallatire
6060
Chile
Cotopaxi
5897
Ecuador
Lascar
5592
Tupungatito
5640
Popocate-petl
5451
Mexico
Altiplano de Mexico
1920
Nevado del Ruiz
5400
Colombia
1985
The Process of Chemical Weathering Solution: It involves the dissolution of soluble particles and minerals from the rocks with the help of water. Oxidation: It represents addition of oxygen to form oxides. Carbonation: It is the reaction of carbonate or bicarbonate ions with minerals. Hydration: It is the process of addition of water to the minerals. Hydrolysis: It is the process wherein both minerals of rocks and water moleclues decompose and react in such a way that new mineral compounds are formed.
▸ Formed due to the cooling, solidification and crystallisation of hot and molten magma. ▸ They are called as the primary rocks as all the other rocks are formed directly or indirectly from the igneous rocks. ▸ It is believed that the igneous rocks are formed during each period of geological history of Earth. ▸ They are hard, granular and crystalline rocks, less affected by chemical weathering. ▸ Moreover, it does not have any fossil or does not form any strata or layers of lava. Classification of Igneous Rocks On the basis of Mode of Occurrence : ▸ Intrusive Rocks They are formed due to the solidification of rising magma below the surface of the Earth, e.g. Granite, Lapolith, Batholiths, Sills etc ▸ Extrusive Rocks They are formed due to cooling and solidification of hot and molten magma at the Earth surface, e.g. Basalt, Gabbro etc. On the basis of Silica Content ▸ Acidic : It has more silica content e.g. Granite. ▸ Basic : It has less amount of silica content e.g. Gabbro.
▸ The word 'Sedimentary' is derived fromthe Latin word sedimentum, which means settling. ▸ It is formed due to the aggregation and compaction of sediments derived from the older rocks, plants, animals and contains fossils of plants. ▸ The sedimentary rocks can be classified on the basis of the nature of sediments : mechanically, chemically and organically formed rocks. Mode of Formation Mechanically Formed Sandstone Conglomerate Chemically Formed Gypsum, Salt rock Organically Formed Limestone,Coal, Peat, Dolomite
▸ These are the changed form of Igneous and Sedimentary rocks. ▸ These are the rocks, which change either in form or composition without disintegration. ▸ Already formed metamorphic rocks are metamorphosed and this process is called metamorphosis. ▸ The agents of metamorphism are heat, compression and solution. Rock Transformation
Marble
Sandstone
Quartzite
Shale/Clay
Slate, Phyllite, Schist
Coal
Diamond
Original Rocks
Metamorphic Rocks
Limestone
Shale and Mudstone
Slate
Granite
Gneisse
Graphite Coal
Clay
The Rock Cycle
▸ There are four major landforms such as mountains, hills, plateau and plains.
Plains
41
Plateau
33
Hills
Mountains
Based on their mode of formation four main types of mountain can be distinguished. FoldMountains ▸ It is formed due to the compressive forces generated by endogenetic forces (earthquake, landslide etc.) ▸ Example of fold moutains : Himalayas, Alps, Andes, Rockies, Atlas etc. On the basis of age, fold mountains are grouped into (a) Young/New Fold Mountains It came into existence after the continental drift. e.g. Himalayas, Andes, Rockies, Alps. Himalayas are regarded as the youngest mountains in the world. (b) Old Fold Mountains They belong to pre-drift era, then subject to denudation and uplift. e.g. Pennines (Europe), Appalachians (US), Aravallis (India) etc.
BlockMountains ▸ It is formed when great block of Earth's crust may be raised or lowered due to tectonic activities. ▸ The land between the two paralled faults either rises forming Block mountains or horsts or subsides into a depression termed as Rift valley or Graben. ▸ Example of Block mountain : Vindhyan and Satpura in India, the Vosges in France and Black forest in Germany (through which Rhine river flows).
VolcanicMountains ▸ They are formed due to the accumulation of volcanic material. ▸ It is also called as Mountains of Accumulation. ▸ Examples : Mt Fuji (Japan), Cotopaxi in Andes, Vesuvius and Etna in Italy, Mt Mayon (Philippines) etc. Residual or DissectedMountains ▸ They are formed as a result of erosion of plateaus and high planes by various agents of erosion. ▸ Examples : Catskill mountains of New York, Sierras of Spain, Highlands of Scotland and Nilgiri, Parasnath, Girnar, Deccan Plateau and Rajmahal of India. Major Mountain Ranges Ranges Locations Length (km)
South America
7200
Himalayan, Karakoram and Hindu kush
South Central Asia
5000
Rockies
North America
4800
Great Dividing Range
East Australia
3600
Atlas
North-West Africa
1930
Caucasus
Alaska
USA
1130
Alps
1050
▸ Tabular upland having relief of more than 500 feetmay be defined as plateau. ▸ Tibetan plateau (5000 m) is the highest plateau in the world. Major Plateaus
Tibetan Plateau
Between Himalayas and Kunlun mountains
Deccan Plateau
Southern India
Arabian Plateau
South-West Asia
Plateau of Brazil
Central-Eastern South America
Plateau of Mexico
Plateau of Colombia
Plateau of Madagascar
Madagascar
Plateau of Alaska
North-West North America
Plateau of Bolivia
Andes Mountains
Great Basin Plateau
South of Colombia Plateau, USA
Colorado Plateau
South of Great Basin Plateau, USA
According to their mode of formation and their physical appearance, plateaus may be grouped into the following types: Tectonic Plateau These are formed by Earthmovements, which cause uplift and are normally of a conside rable size and fairly uniform altitude. ▸ When plateau are enclosed by Fold moutains, they are known as Intermont Plateau. ▸ Examples of Tectonic Plateau are: Tibetan Plateau between the Himalayas and the Kunlun and the Bolivian Plateau between two ranges of the Andes. Volcanic Plateau These are formed by accumulation of lava. e.g. North-Western part of Deccan Plateau (India). Dissected Plateau Through the continual process of weathering and erosion by running water, ice and winds, high extensive plateau are gradually worn down, and their surface made irregular as example is the Scottish Highlands.
▸ A relatively low-lying and flat land surface with least difference between its highest and lowest points is called a Plain. ▸ The plains are divided into structural, erosional and depositional plains. Classification of Plains
Structural Plain
Erosional Plain Depositional Plain
Formed due to the uplift of a part of the sea floor e.g. the Great Plain of USA.
Formed when the Formed by elevated tract of filling up of land is worn down sediments into to a plain by the depressions process of along the erosion. e.g. Plain foothills, lakes of North Canada. and seas e.g. Indo Ganga Plain.
Atmosphere is a thick gaseous envelope surrounding the Earth from all sides and attached to Earth through the force of gravitation. Significance of Atmosphere ▸ Acts as a filter because it absorbs the various unwanted radiation. ▸ Source to various gases. ▸ Supports life forms in biosphere.
Almost 97% of effective atmosphere confines within the height 29 km of the Earth's surface. So, the vertical distribution of the atmosphere is not uniform and even not homogeneous. It extends about 600 miles from the sea level.
▸ The atmosphere is composed of gases, vapours and particulates. ▸ Gases such as Helium, Ozone and Hydrogen etc are present in traces. ▸ Ozone gas absorbs the ultraviolet radiations and save the biosphere from its adverse impact.
Troposphere ▸ It extends up to 18 km from the Earth's surface. Thickness varies from 8 km at the poles to 18 km at the equator. ▸ At every 165 m, there is a drop of 1° C(or 6 4 . ° C per km). This is called Normal Lapse Rate of Temperature. ▸ Tropopause separates troposphere from stratosphere. ▸ This, layer accounts for practically the entire water vapour, all dust particles and most of the Carbon dioxide contained in the atmosphere. Due to this all weather phenomena such as condensation, precipitation and storms etc occur in the troposphere only. Stratosphere ▸ The stratosphere extends up to about 50 km, where stratopause separates it from the mesosphere. ▸ In this layer, the temperature increases with increase in height. This phenomenon is known as temperature inversion. ▸ The temperature rises in this layer from about–60°C at the tropopause to 0°C at stratopause. ▸ The part of the stratosphere, in which there is a concentration of ozone is often called ozonosphere. It absorbs ultraviolet radiation, which is harmful for us. ▸ Stratosphere is free from dust particles and also from atmospheric turbulences. Hence, this layer is considered ideal for flying of jet aircrafts. Mesosphere ▸ Mesosphere extends above the stratopause up to a height of about 80 km. ▸ In this layer, the temperature decreases with height like in the troposphere and it falls from about 0° C at its base to about – 100° Cat 80 km height. It is considered the coldest layer of the atmosphere. ▸ The upper limit of the mesosphere is marked by the Mesopause, a transitional layer separating it from the ionosphere. Ionosphere ▸ Ionosphere is located above the mesosphere and extends up to about 600 km. This layer is also called as ionosphere because it contains electrically charged ions that reflect the radio waves back to the Earth thus making radio communication possible. Absorption of solar radiation by ionised particles cause an increase in temperature with increasing height in the ionosphere. ▸ Due to large concentration of ionised particles in this layer the ionosphere acts as a protective layer against meteorites, that are burnt in this layer.
The percentage composition of the various gases in atmosphere upto 50 kmis given below:
Nitrogen
78.08%
Acts as dilutent and is generally chemically inactive.
21%
Inhaled by biotic components for survival. Oxygen is also essential for combustion of burning matter.
Argon
0.93%
Inert gas.
Carbon dioxide
0.03%
Being a greenhouse gas, it increases the temperature of the lower atmosphere.
Neon
0.0018%
Thermosphere ▸ The zone between the 85 km and 600 km above the surface is often called Thermosphere. In this layer, the temperature increases with increasing altitude. The upper limit of the thermosphere, the thermopause is generally taken at an altitude of about 600 km. ▸ The day temperature at 600 km altitude exceed 1400° C while night temperature remain about 225° C. ▸ The upper part of the thermosphere contains only the lighter gases like helium and hydrogen. Exosphere andMagnetosphere ▸ The outermost part of the atmosphere of the Earth is called Exosphere. ▸ This zone of the atmosphere is about 10,000 km thick. ▸ The upper limit of the exosphere is uncertain as this layer acts as a transitional layer between the Earth's atmosphere and the space. The outer part of the exosphere is called Magnetosphere.
▸ Homosphere up to 90 km In this region, the proportion of various constituents is same throughout. But these days concentration of CO2 is increasing due to global warming whereas concentration of O3 is decreasing due to growing industrialisation. Thus, disturbing the homogeneity. ▸ Heterosphere The recent data from the satellites studies suggested that beyond about 100 km the lightest gases separates out, forming several concentric layers around the Earth. Four distinct layers of gases are mostly registered.
Molecular Nitrogen
100-200
Atomic Oxygen
200-1100
Helium Layer
1100-3500
Hydrogen
No upper limit
Structure of the Atmosphere
▸ Solar radiation that is intercepted by the Earth is known as Insolation. ▸ Insolation is measured with the help of Pyranometers. The amount of insolation depends on following factors: (i) The area and nature of the surface. (ii) The inclination of the rays of the Sun. (iii) Distance between the Earth and the Sun. (iv) Length of the day. (v) The transparency of the atmosphere. ▸ As the angle of the Sun's rays decreases poleward, the amount of insolation received also decreases in that direction. ▸ The Earth's surface does not absorb all the energy that it receives. The proportion of the solar radiation reflected from the surface is called Albedo. ▸ On an average, insolation is highest near the equator, marginally lower at the tropics and lowest at the poles.
▸ The Earth receives energy continuosuly from the Sun, its temperature is almost constant except the long-term climate changes. This is because the atmosphere loses an amount of heat equal to the gain through insolation. This mechanism of maintaining the same temperature by the atmosphere is called the Heat Budget or Heat Balance. ▸ Let us assume that 100 units of energy reach the top of the atmosphere of the Earth, 14 units are absorbed directly by the atmosphere and 35 units are lost to space through reflection. ▸ The remaining 51 units reach the Earth's surface and are absorbed by the Earth due to which the surface gets heated. ▸ The heated surface of the Earth starts radiating energy in the form of long waves and this process is called Terrestrial Radiation. ▸ Out of the total 51 units given up by the surface in the form of terrestrial radiation, the atmosphere (mainly CO2 and water vapour) absorbs about 34 units and the remaining 17 units escape to space. ▸ In this way, the atmosphere receives a total of 14 + 34 = 48 units and this amount is radiated back to space by the atmosphere. ▸ The total loss of energy to space thus amounts to 100 units. 35 units reflected by the atmosphere. 17 units lost as terrestrial radiation 48 units from the atmosphere. 100 units back to space. ▸ In this way, no net gain or loss of energy occurs in the Earth's surface. The transfer of heat is done by two ways (i) Earth's surface to atmosphere (ii) From equator to poles
▸ Air is an extremely compressible gas having its own weight. The pressure exerted by air due to its weight is called atmospheric pressure on the Earth's surface. ▸ Atmospheric pressure is neither the same for all the regions nor the same for one region all the time. ▸ Atmospheric pressure is affected by various factors such as altitude, temperature and Earth's rotation.
Altitude Air pressure increases, when air descends due to the decrease in volume. When air raises its volume increases and the outward pressure of its molecule is spread over a larger area and its pressure decreases. Temperature The pressure of air rises, when its temperature falls. Low temperature at the poles cause the air to contract–high pressure develops; whereas the high temperature along the equator cause the air to expand–low pressure develops.
▸ It is located on either side of the geographical equator in a zone extending between 5°N and 5°S. Its location is not stationary and there is a seasonal drift of this belt with the Northward (summer solstice) and Southward (winter solstice) migration of the Sun. ▸ It is thermally induced because of the intense heating of the ground surface by the almost vertical Sun rays. ▸ It represents the zone of convergence of North-East and South-East trade winds. This convergence zone is characterised by light and feeble winds. and because of the frequent calm conditions this belt is called as a belt of calm or doldrums.
▸ It extends between 30° to 35° in both the hemisphere. ▸ It is not thermally induced, but dynamically induced as it owes its origin to the rotation of the Earth and sinking and settling down of winds. ▸ Here the convergence of winds at higher altitude above this zone results in the subsidence of air from higher altitudes. Thus, descent of wind results in concentration of their volume and ultimately causes high pressure. ▸ This zone of high pressure is also called as Horse Latitude.
Pressure Belt These layers in the order of height are
Layers
The order is in decreasing order of the atomic mass.
▸ It extends between 60° to 65° in both the hemisphere. ▸ The low pressure belt does not appear to be thermally induced because there is low temperature throughout the year and as such there should have been high pressure belt instead of low pressure belt. Thus, it is dynamically induced. ▸ It is more developed and regular in Southern hemisphere than in Northern hemisphere because of the over dominance of water (ocean) in the Southern hemisphere.
▸ High pressure persists at the poles throughout the year because of the prevalence of very low temperature all the year round.
▸ The entire system of pressure and wind belts follows the movement of midday Sun. In June, when the Sun is over the Tropic of Cancer, all the belts move about 5°–10° North of their average position. ▸ In the same manner, when the Sun is overhead at the Tropic of Capricorn in December, all the belts swings 5° –10° South of their average position.
▸ The pressure difference is the major cause of the genesis of the wind system. The air moves from high pressure to low pressure. ▸ The slope of pressure from high to low is called as pressure gradient, which is also called as barometric slope. ▸ The imaginary line joining the points having same pressure is called isobars. The direction of air movement should be perpendicular to the isobars because the direction of pressure gradient is perpendicular to the isobars, but the direction is deviated from the expected one due to Coriolis force caused by the rotation of the Earth. ▸ Thus, the factors that control the air motion are as follows: ▸ Pressure gradient ▸ Rotation of Earth and Coriolis force ▸ Frictional force ▸ Centrifugal action of wind ▸ The winds blowing parallel to the isobars generally at the height of 600 m is called geostropic wind.
▸ The Coriolis force generated due to the rotation of Earth acts as a deflective force to the wind direction. Because of the Coriolis force, all the winds are deflected to the right in the Northern hemisphere while they are deflected to the left in the Southern hemisphere with respect to the rotating Earth. ▸ This is referred to as Farrel's Law. The Coriolis force is absent along the equator, but increases progressively towards the pole. Primary Movement (Permanent Winds) ▸ Trade winds ▸ Westerllies ▸ Polar winds Secondary Movement ▸ Cyclone : Tropical and Temperate, Thunderstorms and Tornado ▸ Anti cyclone ▸ Seasonal wind i.e. Monsoon ▸ Tertiary Movement PrimaryWindMovement (PermanentWinds) These winds include trade wind, westerlies and polar winds. TradeWind ▸ These are steady currents of air blowing from the sub-tropical high pressure belt towards the equatorial low pressure belt. ▸ Under the influence of the Coriolis forces they flow from the North-East in the Northern hemisphere and from South-East in the Southern hemisphere. Westerlies ▸ The permanent winds blowing from the sub-tropical high pressure belt to the sub-polar low pressure belt in both the hemisphere is called Westerlies. ▸ The general direction of the westerlies is South-West to North- East in the Northern hemisphere and North-West to South-East in the Southern hemisphere. ▸ Because of the dominance of the land masses in the Northern hemisphere the Westerlies become more complex and complicated and become less effective during summer seasons and more vigorous during winter seasons. The Westerlies become more rigorous in the Southern hemisphere because of the lack of land and dominance of oceans. ▸ Their velocity increases Southward and they become stormy so they are called roaring forties between latitudes 40°-50°. South latitudes, furious fifties at 50° South latitude and screaming sixties at 60° South latitudes. PolarWinds Polar winds blows from polar high pressure belt to sub-polar low pressure belt. They are North-Easterly in Northern hemisphere and South- Easterly in the Southern hemisphere. SecondaryWindMovement Seasonal winds are the winds, which reverse its direction completely every 6 months is called Seasonal winds. The best example is Monsoon winds.
Cyclones are the centres of low pressure surrounded by closed isobars having increasing pressure outward and closed air circulation from outside towards the central low pressure in such a way that ▸ Air blows inward in anti-clockwise direction in the Northern hemisphere. ▸ Air blows inward in clockwise direction in the Southern hemisphere. Cyclones are mainly of two types (i) Tropical Cyclone (ii)Temperate Cyclone Cyclone Distribution
Tropical Cyclone
Temperate Cyclone
They are found in the trade wind belt, between 8-20 degree North and South. But not found between 0 to 8 degree as there is no coriolis force.
Normally found between 30 to 65 degree North and South in the sub-polar frontal zone, where cold polar air mass meets the warm tropical air mass.
Tropical cyclones are much smaller with a diameter of about 200 to 500 km.
They forms over a much large area with the diameter 300 to 1500 km.
Tropical cyclones are non frontal in nature.
Temperate cyclones are frontal in nature.
It is formed only over the oceans.
It is formed either over continents or over the oceans.
Tropical cyclone can form only in the summer.
They can form both in summer as well as in winter.
It does not have definite lifecycle and weather forecasting is very difficult.
It takes more time to dissipate as it has a more definite lifecycle.
▸ They are the wind system, which has the highest air pressure at the centre and lowest at the outer margins surrounded by circular isobars where wind blows ▸ from centre to outward in clockwise direction in Northern hemisphere. ▸ from centre to outward in anti-clockwise direction in Southern hemisphere. ▸ They are high pressure system and common in sub-tropical belts and practically absent in the equator region. ▸ They are generally associated with rainless fair weather and that's why they are called as weatherless phenomena. Thunderstorms ▸ Thunderstorms are local storm characterised by swift upward movement of air and heavy rainfall with cloud thunder and lightening. ▸ Structurally, thunderstorms consist of several convective cells, which are characterised by strong updraft of air. Tornado ▸ Tornadoes are very strong tropical cyclones of smaller size. In the Mississippi valley (US), they are called Twisters. ▸ They are more destructive than cyclones as the speed of winds is very high, exceeding 220 km per hour. Jet Stream ▸ The strong and rapidly moving circumpolar Westerly air circulation in a narrow belt of a few hundred kilometres width in the upper limit of troposphere is called Jet Stream. ▸ Their circulation path is wavy and meandering. ▸ The extent of the Jet Streams narrows down during the summer season because of their Northward shifting while these extend up to 20° North latitude during winter season.
▸ Humidity of air refers to the content of the water vapour present in the air at a particular time and place. Humidity is measured by an instrument called hygrometer. Another instrument used for the same purpose is sling psychrometer. The atmospheric humidity is expressed in a number of ways such as:
Humidity Capacity
The capacity of air of certain volume at certain temperature to retain maximum amount of moisture content.
Absolute Humidity
The total weight of moisture content per volume of air at definite temperature is called absolute humidity.
Specific Humidity
The mass of the water vapour in grams contained in a kilogram of air and it represents the actual quantity of moisture present in a definite air.
Relative Humidity
It is the ratio of the amount of water vapour actually present in the air having definite volume and temperature (i.e. absolute humidity) to the maximum amount the air can hold (i.e. humidity capacity).
Relative Humidity = × Absolute humidity Humidity capacity 100 ▸ Condensation is the change of physical state of matter from gaseous phase into liquid phase and is the reverse of vaporisation. ▸ When the relative humidity reaches 100%, the air is completely saturated. The air temperature is said to be as dew-point. ▸ Smog (Smoke + Fog) is a form of fog that occurs in areas, where the air contains a large amount of smoke. ▸ Fog is made from the droplets of water suspended in the lower layer of the atmosphere. Fog is not considered as a form of precipitaion. Visibility of less than 1 km is the internationally recognised definition of fog. ▸ Haze is formed by water particles that have condensed in the atmosphere and visibility lie between 1 km to 2 km. ▸ Frost is the moisture on the ground surface that condenses directly into ice, i.e. when condensation occurs below freezing point.
On the basis of its origin, precipitation may be classified into four main types ▸ Convectional Rainfall It occurs due to thermal convection currents caused due to insolational heating of ground surface.
▸ Orographic Rainfall occurs due to ascent of air forced by mountain barrier.
▸ Frontal Rainfall It occurs due to upward movement of air caused by convergence of cold air masses against warm air masses. ▸ Cyclonic Rainfall When the air is caused to rise upward due to cyclonic circulation, the resulting precipitation is called cyclonic rainfall. The average weather conditions over a large area are called the climate of a place. Tertiary Movement (Local Winds)
Land Breeze
Warm
Land breeze blows from land to sea.
Sea Breeze
Cold
Sea breeze blows from sea to land.
Chinook (snow eater)
Rockies (USA and Canada)
Sirocco
Hot
North Africa
Fohn
Alps/Europe
Khamsin
Egypt
Blizzard
Siberian, Canada, USA
Bora
Yugoslavia
Southerly Buster
Australia
Purga
Russian, Tundra
Bire
France
Cape Doctor
South African coast
Harmattan (The Doctor)
Sahara to Guinea Coast (Ghana, Nigeria etc)
Zonda
Argentina, Chile/Andes
Brick Fielder
Samun
Iran
Levanter
Cold Wind
Spain
Norwester
Hot Wind
New Zealand
Leveche
Algeria, Morocco
Santa Ana
USA (California)
Berg
South Africa
Yoma
Karaburan
Tarim Basin
Black Roller
Hot/Dusty
Kalbaisakhi
North India
Mistral
France to Mediterranean (Rhine valley)
▸ The factors, which control the weather and the climatic conditions are latitude, altitude, unequal distribution of land and water, ocean current, air pressure and wind, mountain barrier, nature of ground surface, different types of atmospheric storms etc. Types of Precipitation
Convectional Precipitation
Orographic Precipitation
Cyclonic Precipitation
It occurs daily in the afternoon in the equatorial regions. It is of very short duration but occurs in the form of heavy rainfall. It occurs through thick, dark and extensive cumulonimbus clouds. It is accompanied by cloud, thunder and lightening.
The wind ward slope receives the maximum amount of rainfall, whereas the leeward side receives less rainfall. The windward slopes of the mountains at the time of rainfall are characterised by cumulus clouds while leeward slope has stratus clouds. It can occur in any season.
Rainfall associated with the temperate cyclone occurs, when two extensive air masses of different physical properties converge. In tropical regions two extensive air masses of similar physical properties converge to form tropical cyclones, wherein lifting of air is almost vertical and very often associated with convection.
▸ Clouds are the masses of small water droplets or tiny ice crystals. ▸ Clouds are classified according to their appearance, form and height. There are four groups (i) High Clouds 6000 m to 12000 m (ii) Middle Clouds 2100 m to 6000 m (iii) Low Clouds below 2100 m (iv) Clouds of great vertical extent 1500 m to 9000 m The different types of clouds are given Latin names, which are the combination of the following words: ▸ Cirrus means looking like a feather and used to describe the very high clouds. ▸ Cumulus means looking like a heap. It is used to describe the clouds having flat bases and rounded tops. ▸ Stratus means lying in level sheets. It is used for layer type of clouds. ▸ Alto means high. ▸ Nimbus means rain cloud. Types of Clouds
High Clouds
Middle Clouds
Low Clouds
Clouds with Great Vertical Extent
Cirrus Composed of small ice crystal, white, wispy and fibrous in appearance.
Alto-cumulus Composed of water droplets in layers and patches.
Strato-cumulus Large globular masses, bumpy looking, soft and grey in appearance forming a pronounced regular and sometimes wavy pattern.
Cumulus Round topped and flat based forming a whitish grey globular mass, consists of individual cloud units.
Cirro-cumulus Composed of ice crystals, but globular or rippled in appearance.
Alto-stratus Composed of water droplets, forming sheets of grey or watery looking clouds.
Nimbo-stratus Dark grey and rainy looking, dense and shapeless, often gives continuous rains.
Cumulo-nimbus They have a great vertical extent, white or black globular masses, whose rounded tops often spread out in the form of anvil. It is characterised by convectional rain, lightning and thunder.
Cirro-stratus Looks like a thin white almost transparent sheet, which causes the Sun and Moon to shines through it with a characteristic 'halo'.
Stratus These are low, grey and layered, almost fog like in appearance, bringing dull weather and often accompanied by drizzle.
Noctilucent clouds, they are made of ice crystals. They are normally too faint to be seen.
Weather refers to the sum total of the atmospheric conditions in terms of temperature, pressure, wind, moisture, cloudiness, precipitation and visibility of a particular place at any given time. Great Deserts
Sahara (Libyan, Nubian)
Australian (Gibson, Simpson, Victorian Great Sandy)
Arabian (Rub-al-Khali, An-Nafud)
Arabia
Dast-e-Lut (Barren Desert)
Dast-e-Kavir (Salt-e-Kavir) (Salt Desert)
Desier to de Sechura
Peru
Atacama
North Chile
Patagonia
Argentina
Kalahari
Botswana
World Climatic Types
Climatic Zone
Climatic Types
Natural Vegetation
Equatorial Zone (0°-10°N and S)
1. Hot, wet equatorial
Rainfall all the year (80 inches)
Equatorial rain forests
Hot Zone
2. (a) Tropical Monsoon
Heavy summer rain (60 inches)
Monsoon forests
(10P-30°N and S)
(b) Tropical Marine 3. Sudan type
Rain mainly in summer (70 inches)
Savana (Tropical grassland)
4. Desert (a) Saharan type
Little rain (5 inches)
Desert vegetation and scrub
(b) Mid latitude type
Warm Tern per ale Zone (30°N-45°S)
5. Western margin (Mediterranean type) 6. Central Continental type (Steppe type)
Winter rain (35 inches) Light summer rain (20 Inches)
Mediterranean forests Steppe, temperate grassland
7. Eastern Margin
Heavier summer rain (45 inches)
Warm, wet forests and bamboo
(a) China type
(b) Gulf type
(c) Natal type
Cool Temperate Zones
8. Western Margin (British Type)
Rain in autumn and winter (30 inches)
Deciduous forests
(45ON-65°S)
9. Central Continental (Siberian Type)
Light summer rain (25 inches)
Coniferous forests
10. Eastern Margin (Lauritian Type)
Moderate summer rain (40 inches)
Mixed forests (coniferous and deciduous)
Cold Zone (65°N-90°S)
11. Arctic or Polar
Very light summer rain (10 inches)
Tundra, mosses, lichens
12. Mountain Cimate
Heavy rainfall (variable)
Alpine, fern, coniferous, pastures, snow
Hot Wet Equatorial Climate
Climate
Economy
Found between 5°N -10°S of the equator. It is found mainly in the lowlands of Amazon, Congo, Malaysia and the East Indies.
Mean monthly temperature around 24-27 degree C. Diurnal and annual range of temperature is small. Convectional rainfall with annual rainfall of 250 cm.
Tropical rain forest with multitude of evergreen trees such as mahogany, ebony. Lianos, epiphytic and parasitic plants are also found.
Sparsely populated primitive people live as hunter and gatherer in the forests. Practice of shifting cultivation is prevalent.
Tropical Monsoon and Tropical Marine Climate
Found between ▸ 5°-30° latitudes on either side of the equator. It is found mainly in ▸ India, Burma, Thailand, Laos, Cambodia, Northern ▸ Australia . ▸
Summer and winter seasons are sharply differentiated due to the North and Southward movement of the Sun. Average temperature of warm dry summer months ranges between 27-32° C. Orographic and Cyclonic Rainfall Monsoon rain through South-West monsoon winds.
Normally deciduous. Most of the forest yield ▸ valuable timber like teak, sal, acacia etc.
Agriculture based economy. Agriculture crops includes rice, sugarcane, jute etc.
The Sudan or Savanna Climate
Located between ▸ 5°-20° latitude on either side of the equator. Mostly found in Llanos of Orinoco valley, the ▸ Campos of Brazil, hilly areas of Central America, Southern Zaire etc.
Alternate hot, rainy and cool dry season. Mean high temperature throughout the year is between 24 and 27 degree C. The extreme diurnal range ▸ of temperature is a characteristic of Sudan type of climate. The average annual rainfall ranges between 100 cm and 150 cm.
Characterised by tall grass and short trees (flat top). Trees are ▸ deciduous and hard. Scrubland is well represented by a number of species ▸ in Australia like mallee, mulga, spinifex grass etc.
Tribes live in the Savanna lands. Some tribes live as Pastoralists like the Maasai. Hausa are settled as cultivators in Northern Nigeria.
Hot Desert and Mid – Latitudinal Desert Climate
Major hot deserts are located on the Western coasts of continents between latitudes 15°N-30°S.
Lie on the sub- tropical high pressure belt, where air is descending. Relative humidity is extremely low. Rainfall is convectional type with violent thunder storm. The diurnal temperature is very high.
Vegetation is mostly Xerophytic or drought resistant scrub. Plants that exist in deserts have highly specialised means of adapting themselves to the arid environment such as few or no leaves, needle shaped leaves etc.
Inhospitable conditions of the deserts are barrier to economic development. The Bushmen of the Kalahari and the Bindibu of Australia are primitive tribes.
Warm Temperate Western Margin : Mediterranean
This is found in ▸ California, in parts of Western and South Australia, in South-Western ▸ South Africa in parts of Central Chile and around the Mediterranean region.
The climate is characterised by hot, dry summers and cool, wet winters. During summer, regions of Mediterranean climate are dominated by sub-tropical high pressure cells causing no or little rainfall.
Evergreen trees such as oak and eucalyptus, jarrah and kari are found. Evergreen coniferous trees are pines, firs, cedars and cypresses.
Economy is based on cultivation of fruits, wine making and cereal growing and a wide range of citrus foods.
Temperate Continental Steppe Climate
Pustaz of Hungary, Prairies of North America, Pampas of Argentina and Uruguay, Bush Veld of South Africa.
Continental climate with extremes of temperature. Winters are very cool.
It has the scanty vegetation of the sub-arid lands of continental Eurasia.
Grazing of animals, extensive and mechanised wheat cultivation.
Warm Temperate Eastern Margin : China Type (Gulf Type Climate)
Found on the Eastern margin of the continents in warm temperate latitudes.
Characterised by warm moist summer and a cool dry winter. Uniform distribution of rainfall throughout the year is an important feature.
Evergreen broad leaved forests and deciduous forests.
Rice, tea and mulberries are extensively grown in monsoon China. Other important crops are corn, tobacco and cotton.
Cool Temperate Western Margin : British Type
From Britain, this belt stretches far inland into the lowlands of North-West Europe including regions such as Northern and Western France, Belgium, the Netherland, Denmark, Western Norway.
It is under the permanent influence of the Westerlies. Summers are in fact never very warm. Winters are mild. As the rain bearing winds come from the West, the Western margins have the heaviest rainfall.
Deciduous forest some of the common species are oak, elm, birch, beech, poplar etc.
Fishing is important in Norway and British Columbia. Market gardening is widely practised in North-Western Europe.
Cool Temperate Continental : Siberian (Boroeal Type)
Experienced only in Northern hemisphere. On its polar side, it merges into the Arctic Tundra and in Southern side, it fades into the temperate steppe climate.
Characterised by a bitterly cold winter of long duration and a cool brief summer. The winter precipitation is in the form of snow.
Here the Coniferous forest belt of Eurasia and North America are the richest source of the softwood. The major species are pine, fir spruce and larch.
Saw mills for the softwood are prevalent. Many of the Samoyeds and Yakuts of Siberia and some of the Canadians are engaged in hunting, trapping and fishing.
Cool Temperate Eastern Margin : Laurentian
It is found in North- ▸ Eastern North America and the Eastern Coast of Asia. It is absent in Southern hemisphere because only a small portion of Southern continents extend South of the latitude of 40° South.
It has cold dry
Generally forest is winter and warm, Coniferous. Some wet summers. of the important Winters species are oak, temperature may maple and birch. be well below freezing point and snow falls to quite a depth.
Lumbering and its associated timber, paper and pulp industries are the most important economic under- taking.
Arctic and Polar
It is found mainly in North of the Arctic circle.
Characterised by a very low mean annual temperature. Winter are long and very severe, ▸ summers are cool and brief. Precipitation is mainly in the form of snow falling in winter.
The greatest ▸ inhibitating factor is the region's deficient in heat. There are no trees in the Tundra. ▸ Such an environment can support only the lowest form of vegetation, mosses, lichens and sedges.
The few people, who live in the Tundra live a seminomadic life. Eskimos live in Greenland, Northern Canada and Alaska. In the Eurasian Tundra, there are other nomadic tribes such as the Lapps of Northern Finland and Scandinavian, the Samoyeds of Siberia, Yakuts, Koryaks and Chuckshi of North- Eastern Asia.
Famous Grasslands of the World
Steppe
Eurasia
Pustaz
Hungary
Prairie
Pampas
Veld
Downs
Cantebury
Some Important Isopleth
Isohels
Sunshine
Isohyets
Rainfall
Isonif
Snow
Isocline
Slope
Isotherms
Temperature
Isobars
Equal Pressure
Isabath
Equal depth in sea
Isohaline
Salinity
Isohypse
Elevation above sea-level
Isodapane
Equal transportation cost
Isobrants
Thunder storm at the same time
The water component of the Earth is called hydrosphere which covers about 70% of the surface of Earth. It includes the oceans, seas, lakes, ponds, rivers and streams. Composition of Hydrosphere
Oceans
97.6
Ice capes and glaciers
2.05
Ground water
0.68
Soil moisture
0.01
Saline lakes and inland seas
0.008
Lakes
0.009
Freshwater rivers
0.0001
0.0009
There are four oceans. In the order of their size they are: Pacific ocean, Atlantic ocean, Indian ocean and Arctic ocean. The average depth of oceans is about 4 km.
Pacific
It is the largest and deepest ocean. Most of the Islands of the ocean are volcanic or of coral origin. Mariana Trench, the world's deepest trench with depth 11033 km is in Pacific ocean.
Atlantic
It has the longest coast line. It is the busiest ocean for trade and commerce since its sea routes connect the two most industrialised regions, namely Western Europe and North-Eastern United States of America. Atlantic ocean is still widening. Puerto Rico Trench is the deepest point of this ocean.
Indian
Only ocean named after a country. It is deeper than the Atlantic ocean. Here the number of continental islands is more than that of volcanic islands. Sunda (farlier known as java) Trench is the deepest point of this ocean.
Arctic
It is the smallest ocean and lies within the Arctic circle. The North pole lies in the middle of the Arctic ocean. Most of the part of the ocean is frozen and hence least saline and the shallowest among all the oceans. Nansei Trench is the deepest point of this ocean.
▸ The shallow sub-merged extension of the continent is called the continental shelf. ▸ Extends to a depth of 100 fathoms (1 fathoms = 18 . m). ▸ Average width 70 km; average slope 17 feet/mile or about 1°. ▸ Continental shelf covers 7.5% area of the oceans. It extends over 13.3% of the Atlantic ocean 5.7% of Pacific ocean and 4.2% of Indian ocean. ▸ If mountains extend along the coast, the shelf will be narrower. ▸ About 20% petrol and gas are found here. They also provide the richest fishing ground in the world.
▸ Extends seawards from the continental shelf. ▸ Depth-200-2000 fathoms (3660 m). ▸ Average slope 2 to 5 degrees. ▸ The boundary between shelf and slope is known as Andesite Line, names after the Andesite Rock. ▸ They cover about 8.5% of the total ocean area.
▸ Continental rise is an area at the foot of the slope, slightly rising due to the accumulation of debris transported over the slope. ▸ Average slope-0.5° to 1°. ▸ Oil deposits occur here.
▸ It is the deepest and most extensive part of the oceanic floor. ▸ Average depth 3000 m to 6000 m. ▸ It covers about 75.9% of total oceanic area. ▸ Parts of the Abyssal plains are occupied by raised ridges or submarine mountains and by very deep trenches or canyons.
▸ Trenches are narrow and steep sides depressions. Trenches are formed, when two plates of the Earth's crust are moving together and one is being pushed down below the other. ▸ Mariana trench (Challenger deep) is the deepest trench in the world situated in the NWPacific oceans, near Philippines. It is more than 11 km deep.
▸ Oceanic Ridges are formed by the volcanic activity along the spreading boundary of plates. ▸ It is thousands of km long and hundreds of km wide mountain range on the oceanic floor. ▸ Their summits may rise above the sea level in the form of Islands i.e. Azores Island of Iceland. Land Continental shelf Continental slope Continental rise Trench Submarine ridge Guyot Sea mount Deep sea plain forming island Relief of the Ocean Basin
▸ A ridge rising more than 1000 m above the ocean floor is called seamount. Flat topped sea mounts are called Guyouts. ▸ Both of them are formed by the volcanic activity. ▸ Largest number of sea mounts and Guyouts are found in the Pacific.
▸ Submarine canyons are the deep gorges on the ocean floor and are restricted to the continental shelves, slopes and rises. ▸ Many submarine canyons are found along the mouths of major rivers e.g. Hudson canyon.
▸ Coral reefs are formed due to accumulation and the compaction of skeletons of lime secreting organisms known as Coral Polyps. ▸ Corals are found mainly in the tropical oceans and seas because they require high mean annual temperature of ranging between 20°C to 25°C. ▸ Corals do not live in deeper waters due to lack of sufficient sunlight and oxygen. On the basis of nature, shape and mode of occurrence, the coral reefs is classified into four types:
▸ It develop along the continental margins or along the islands. ▸ The seaward slope is steep and vertical while the landward slope is gentle. ▸ They are usually attached to the coastal land, but occasionally they are separated from the shore by a shallow and narrow lagoon called Boat Channel. ▸ This type of reefs are found near Rameshwaram in the Gulf of Mannar and Andamans.
▸ Largest coral reefs off the coastal platform, but parallel to them. The reef lies at a distance away from the coast. Hence, a broad lagoon develops between the reef and the shore. ▸ The Great Barries Reef of Australia is the largest barrier reef in the world. In India found in Nicobar and Lakshadweep.
▸ Patch reefs are isolated and discontinious patches lying shoreward of offshore reef structures. These are found in the Palk bay, Gulf of Mannar and Gulf of Kutch.
▸ A reef of narrow growing corals of horse shoe shape and crowned with palm trees is called an atoll. ▸ It is formed around an islands or in an elliptical form on a submarine platform. ▸ Funafuti atoll of Ellice Islands is a famous atoll also found in Lakshadweep and Nicobar. Coral Bleaching When corals are stressed by changes in conditions such as temperature, light or nutrients, they expel the symbiotic algae living in their tissues, causing them to turn completely white, this phenomenon is known as coral bleaching.
▸ Salinity is defined as the total amount of salt content in grams contained in 1 kg of sea water and is expressed as part per thousand. The oceanic salinity not only affects the marine organism and plant community, but also affects the physical properties of the ocean such as temperature, pressure, density, waves and currents. ▸ Average salinity in Southern hemisphere is more than that of Northern hemisphere. ▸ Iso-halines represent the salinity distribution in the surface of the sea. These are the lines joining places having an equal degree of salinity. The main source of salinity is dissolution of the rocks of oceanic crust, which contain salts. ▸ Poles have minimum salinity because of addition of fresh water in the form of icebergs and excessive snowfall. ▸ Variation in salinity causes vertical circulation of water. More saline water freezes slowly while the boiling point of saline water is higher than the fresh water. ▸ Salinity also increases the density of water. Composition of Sea Water Salt PercentageComposition (%)
Sodium Chloride
77.8
Magnesium Chloride
10.9
Magnesium Sulphate
4.7
Calcium Sulphate
Potassium Sulphate
2.5
Others
0.5
Most Saline Water Bodies WaterBodiesPercentageComposition (%)
Lake Assel (Djibuti)
34.8
Lake Van (Turkey)
Dead Sea (West Asia)
33.7
Great Salt Lake (USA)
32.0
Salinity on an average decreases from equator to poles. The highest salinity is recorded near the tropics rather than the equator because of the heavy precipitation in the equatorial region.
The salinity of oceans and different seas depends on a number of factors such as evaporation, precipitation, influx of the river water, prevailing wind, ocean currents and sea waves etc.
Evaporation
Greater the evaporation, higher the salinity.
Precipitation
Higher the precipitation, lower the salinity.
Influx of river water
Big voluminuous rivers pour down immense volume of fresh water into the oceans and salinity is reduced at the mouth.
Atmospheric pressure
Anticyclonic conditions with stable air and high temperature increases the salinity of the surface water of the ocean.
Circulation of oceanic water
Ocean currents affect the spatial distribution of salinity by mixing sea waters.
▸ Waves are the oscillatory movements in water mainly produced by winds, manifested by an alternate rise and fall of the sea surface. ▸ The waves are the important agents of erosion in the coastal regions, where they carve out various landforms like caves, bays, gulfs, capes and cliffs. ▸ Seismic waves or Tsunamis are the waves caused by earthquakes in volcanic eruptions in the sea bottom. ▸ The Tsunamis, which hit the coast in South-East Asia on 26th December, 2004, caused havoc in that region.
▸ An ocean current is a continuous, directed movement of ocean water generated by the forces acting upon it, such as breaking waves, wind, coriolis effect, temperature and salinity differences and tides caused by the gravitation pull of the Moon and the Sun. ▸ Ocean currents circulate in clockwise direction in Northern hemisphere and in anti-clockwise direction in Southern hemisphere. Ocean currents are of two types: (i) Warm Currents The ocean currents flowing from lower latitude to higher latitude are called as warm currents. (ii) Cold Currents The ocean currents flowing from higher latitude to lower latitude are called as cold currents.
▸ North Equatorial Current It flows Westwards from the Western Coast of Mexico to the Philippines. ▸ Kuroshio Current It is an extension of North Equatorial Current near Japan Coast. It flows towards North. ▸ Alaska Current It flows along the Coast of British Columbia and the Alaska Peninsula.
▸ Oyashio Current It flows down from Bering Sea towards Japan from North pole and it joins Kuroshio currents. ▸ Kuril Current It flows down from sea of Okhotsk and joins Kuroshio current to the North of Japan. ▸ West Wind Drift It flows towards Alaska. ▸ Californian Current It is an extension of Alaskan currents. It joins finally North Equatorial current and completes clockwise circulation of water.
WarmCurrents ▸ East Australian Current or Great Barrier Current It flows towards East coast of Australia from equator towards Pole. ▸ South Equatorial Current It originates due to South-East trade winds and flows Westwards and bifurcates near New Guinea. ▸ Counter Equatorial Current It extends upto Panama Bay. It flows exactly on equator from West to East.
▸ Peruvian Current (Humboldt current). It flows from South pole towards equator on the Coast of Chile and Peru. ▸ West Wind Drift It flows from Tasmania to Chile Coast of South America.
▸ North Equatorial Current It is present between Equator and 10°N. ▸ Cayenne Current It flows adjacent to French Guinea and enters into Carribean Sea and Gulf of Mexico. ▸ Florida Current Cayenne current near Florida (US Coast) is called Florida current. ▸ Antilles Current It flows to the East of West Indies and Other Islands. ▸ Gulf Stream It flows from US coast towards North-West Europe under the influence of westerly winds. ▸ North Atlantic Drift Gulf Stream bifurcates into (i) North Atlantic Drift (warm) (ii) WestWind Drift (cold) and Canaries current (cold)
▸ Labrador Current It orginates in Baffin Bay and Davis Strait and merges with Gulf Stream near Newfoundland. Newfoundland is a famous zone of fishing, commonly known as Grand Bank. ▸ Irminger Current or East Greenland Current It flows between Greenland and Iceland and merges with North Atlantic drift. ▸ Canaries Current It flows along the Western Coast of North Africa between Madeira cape verde and it joins North equatorial current. ▸ West Wind Drift It flows towards UK.
▸ South Equatorial Current It flows between equator and 10°. ▸ Brazilian Current It flows to the East Coast of Brazil from equator towards pole.
▸ Falkland Current It flows along the South-East Coast of South America from South to North. ▸ Benguela Current It flows from South to North near the 'Cape of Good Hope'. ▸ West Wind Drift It is continuence of Brazilian and Falkland current. ▸ Guinea Current It flows near Coast of Guinea (Africa).
▸ The Asiatic Monsoon influences the currents of the North Indian Ocean, while the currents of South Indian ocean are influenced by the atmosphere's anti-cyclonic circulation. ▸ North Equatorial Current The current flows from East toWest and upon reaching the East Coast of Africa, a good portion turns Southward, crosses the equator, and becomes the Mozambique current. ▸ Mozambique Current The Mozambique current flows South along the East Coast of Africa from the vicinity of the equator to about 35°S, where it becomes Agulhas Stream. ▸ Agulhas Stream The Agulhas stream flows Westward along the Southern West of Madagascar and joins the Mozambique current along the East African coast. ▸ WestWind Drift Current It flows across the Indian ocean to the waters South-West of Australia. ▸ North-East Monsoon Drift It flows along the coast of India during winter. ▸ South-West Monsoon Drift It flows along the coast of India during Summer. ▸ South Equatorial Current It is a significant Pacific, Atlantic and Indian ocean current that flows East-West between the equator and about 20 degrees South. ▸ Somalia Current It is an ocean boundary current that runs along the coast of Somalia and Aman in the Western Indian ocean and is analogous to the Gulf Stream in the Atlantic Ocean. ▸ There is no counter equatorial current in the Indian ocean rather only monsoonal currents which change their direction with respect to seasons.
▸ The rise and fall of the sea level as a result of the forces between the Earth, the Moon and the Sun is called a tide. The interval between two tides is 12 hours and 26 minutes.
▸ When the Earth, the Moon and the Sun are in a straight line also called SYZYGY the Sun assists the gravitational pull of the Moon, creating a condition of higher high tides and lower low tides known as spring tides.
▸ When the Sun and Moon are at right angles to the Earth, the Sun partially contracts the pull of the Moon, producing lower high tides typical of a Neap tide.
Asia, Africa, North America, South America, Europe, Australia and Antarctica are the seven continents. Continent's Earth Area
Asia
29.5
Africa
20.4
16.3
11.8
Antarctica
9.6
7.1
5.3
It has 49 and 5 disputed countries. Latitude 10° S and 80° N Longitude 25° E and 170° W Area 44579000 sq km (approx 30% of the World) Population 4.427 billion Oceans and Seas Arctic Ocean, Pacific Ocean, Indian Ocean, Red Sea, Gulf of Aden, Persian Gulf, Gulf of Oman, Arabian Sea, Bay of Bengal, China Sea, Yellow Sea, Okhotsk and Bering Sea. Highest Point Mt Everest (8848 m) Lowest Point Dead Sea (– 396 m) Straits Strait of Malacca, Bering Strait Islands Kurile, Sakhalin, Honshu, Hokkaido, Taiwan, Borneo, Sumatra and Java, Celebes, New Guinea, Philippines, Sri Lanka, Bahrain and Cyprus. Peninsulas Kamchatka Peninsula, Peninsula of Korea, Peninsula of Indo-China, Malay Peninsula, Indian Peninsula and Arabian Peninsula. ▸ It is the largest continent in the world both in term of the population and area. ▸ It is situated entirely in the Northern hemisphere except some of the islands of Indonesia. ▸ To the North of it lies the Arctic ocean, to the East the Pacific ocean, to the South, the Indian ocean and to the West lies Mediterranean sea. It is separated from Europe by the Ural mountains, the Caspian sea, the Black sea, the Caucasus mountain and the strait of Dardanelles in the West. Important Information of Asia ▸ Caspian Sea is the world's largest lake and five times larger than the Lake Superior. It separates Europe from Asia. ▸ Dast-e-Kavir is the largest salt desert of the world situated in the Northern Iran. ▸ Lop Nor Lake in China is a site for numerous nuclear tests. ▸ Hwang Ho is called as China's Sorrow. It flows through loess land, hence it is also called as Yellow river. ▸ Quinling mountains divide China into North and South China. ▸ Amur river forms the boundary between Russia and China. ▸ Yangtze Kiang is the longest river of Asia. ▸ Mekong river flows through China, Thailand-Laos border, Cambodia and Vietnam to South China sea. ▸ Laos is the only landlocked country in South-East Asian Peninsula. ▸ Group of islands is called an Archipelago. Indonesia is the largest archipelago in the world. ▸ Irawaddy river is known as the lifeline of Myanmar. It falls into Gulf of Martaban. In Gulf of Martaban pearls are found. ▸ Lake Van of Turkey is the most saline water body in Asia. ▸ Fujiyama, a volcanic mountain is the highest peak of Japan. ▸ Japan is the most industralised nation of Asia. ▸ Myanmar is called land of mountains and rivers. ▸ Pakistan is called country of canals. ▸ Japan is called land of Rising Sun. ▸ Dead Sea, the third saltiest water body in the world, is a landlocked sea. It lies between Israel and Jordan. Physical Aspects of Asia
Mountains Himalayas, Karakoram, Kailash, Kunlung Shan, Tienshan, Altai, Sayan, Yablonovy, Stanvoy, Kolyma, Verkhoyansk, Pegu Yoma, Arakan Yoma, Hindukush, Elburz, Sulaiman, Kirthar, Makran, Zagros, Pontic, Taurus.
Rivers
Ob, Yenisey, Amur, Yalu, Hwang Ho, Sikiang, Mekong, Tigris, Eupharates, Amu Darya and Syr Darya.
Baikal, Balkash, Van Golu, Turnool, Asad, Dead Sea, Tonle Sap Toba, Lop Nor, Caspian Sea and Sea of Gallilee.
Manchurian, Great Plain of China, West Siberian Plain, Mesopotamian.
Deserts
Rub-al-Khali, Al Nafud, Dasht-I-Kavir, Dasht -I-Lut, Gobi.
Plateaus
Ladakh, Tibet, Yunan, Takla Makan, Pamir, Armenian, Iranian, Mongolia, Alban, Indo-China, Shan, Deccan, Baluchistan, Arabian, Anatolia, Loess.
Mountains from
South-West: Sulaiman
Pamir Knot
South-East: Himalaya, Karakoram and Kunlun North-East: Tien Shan North-West: Hindukush
South-West : Taurus
Armenian Knot
South-East: Zagros North-East: Elburz North-West: Pontic
Japan Cities
Tokyo
Electrical Instruments
Yokohama
Precision Instruments
Nagoya
Automobiles
Osaka
Cotton Textiles
Nagasaki
It has 54 countries. Latitude 35° S and 37° N Longitude 50° E and 17° W Population 1022234000 (2nd) Area 30065000 sq km (approx) (20.4 % of the world) Oceans and Seas Indian Ocean, Red Sea, Atlantic Ocean, Gulf of Guinea, Mediterranean Sea. Highest Point Kilimanjaro (5895 m) Lowest Point Lake Assal (-156.1 m) Straits Strait of Bab-el-Mandeb and Straits of Gibraltar. Islands Madagascar, Cape Verde Islands, the Comoros, Mauritius and Seychelles. Plateaus The entire continent is a plateau. Three types of palm trees are found in Africa viz Coconut palm, Oil palm and Date palm. ▸ It is the second largest continent after Asia and about nine times the size of India. ▸ It is situated South of Europe and South-East of Asia. It is bound by Mediterranean sea in the North, the Atlantic ocean in the West and South-West, the Indian ocean in the East and Red sea in the North- East. ▸ Africa belongs to all four hemispheres and bulk of the continent lies in tropics. It is joined to Asia by the narrow isthmus of Suez and separated from Eurasia at three different points (Strait of Gibraltar, Suez canal and the strait of Bab-el-Mandeb). ▸ It is the only continent, which is crossed by Tropic of Cancer, Equator and Tropic of Capricorn. ▸ It is also called as Dark Continent because the greater part of its vast interior remained little known to the outside world until the last century. Physical Aspects of Africa
Atlas, Ethiopian Highlands, Mt Kenya, Mt Elgon, Mt Kilimanjaro, Drakensberg, Mt Cameroon, Mt Rouwenzori, Katanga Plateau and Jos Plateau
Nile, Zaire or Congo, Niger, Orange, Limpopo, Zambezi
Kariba, Nyasa, Mweru,Tanganyika, Edward, Tana, Nasser, Chad, Volta and Assal, Victoria
Sahara, Sahel, Libyan, Arabian,Nubian, Namib and Kalahari
Important Information of Africa ▸ Lake Victoria is the largest lake of Africa, which is located between Uganda, Kenya and Tanzania. It is source to White Nile river. The equator passes through it. ▸ Nasser lake is a man-made lake, which lies on Nile river and located between Egypt and Sudan. ▸ Nile river is the longest river of the world and life blood of Egypt. ▸ The White Nile and the Blue Nile meet at Khartoum (Sudan) to form Nile. ▸ Congo river cuts equator twice. ▸ Port Harcourt of Niger is located on Niger Delta. ▸ The Zambezi river includes the Victoria fall, one of the largest falls in the world. It makes the natural political boundary between Zambia and Zimbabwe. ▸ The Orange river forms the natural boundary between South Africa and Namibia. ▸ The Limpopo river cuts the Tropic of Capricorn twice and it separates South Africa from Botswana and Zimbabwe. ▸ The highest peak of Africa is Mt Kilimanjaro and is located in Tanzania. ▸ The three points, where Africa almost touches Eurasia are Gibraltar, Suez and Bab-el-Mandeb. ▸ The highest temperature in the world has been recorded at Al-Aziziyah (Libya) as 58°C making it the hottest place in the world. ▸ Swahili is a famous language of Africa. ▸ Sahara desert is the largest single stretch of desert, which is 5500 km from East to West and 1900 km from North to South. ▸ Kalahari desert is the home of the Africa's one of the oldest races, the Kalahari Bushmen. ▸ Food crops such as wheat, rice, maize and cash crops such as cotton, coffee, cocoa, oil palm, sugarcane, rubber, tobacco are prominent in Africa. ▸ Africa is rich in mineral deposits and these minerals are mostly found on the plateau, South of the Equator. The minerals found in Africa are diamond, gold, copper, bauxite, platinum, iron ore, petroleum, manganese etc.
It has 23 countries. Latitude 7° N and 84° N Longitude 20° W and 180° W Area 24235280 sq km (approx) (16.3 %) Population 528720588 (4th) Major Deserts Chihuahuan, Colorado, Mujave, Sonoran Oceans and Seas Atlantic Ocean, Caribbean Sea, Gulf of California, Gulf of Alaska, Bering Sea and Hudson Bay. Islands Greenland, Baffin, Victoria, New Foundland, Cuba, Jamaica and Haiti. Highest Point Meckinley (6194 m) Lowest Point Death Valley (-85.9 m) ▸ It is the 3rd largest continent after Asia and Africa. It is surrounded by the Atlantic ocean in the East, Gulf of Mexico in the South, the Pacific ocean in the West and the Arctic in the North. To the North it is separated from the Easternmost tip of Siberia by the Bering Strait. ▸ 49° latitude parallel forms the boundary between Canada and USA and 100° W longitude divides the North America into more or less two equal parts. Physical Aspects of North America
Brook’s range, Alaska, Aleutian ranges, Cascade range, Rocky mountains, Coast range, Sierra Nevada etc.
Mississippi-Missouri, St Lawrence, Colorado, Columbia, Sacramento, Rio Grande, Yukon, Mackenzie, Nelson, Saskatchewan Peace etc.
Great Bear, Great Salve, Athabasca, Winnipeg, Superior, Michigan, Huron, Erie, Ontario, Great Salt and Mead.
Columbia-Snake, Colorado and Mexican.
Peninsula
Ungava, Yucatan and Kenai.
Important Information of North America ▸ Canada has the longest coast line in the world. ▸ Canada is the second largest country (in area) in the world. ▸ USA is the fourth largest country in area and third largest country (in population) in the world. ▸ 49th parallel forms the boundary between Canada and USA. It is the longest boundary between two countries. ▸ Erie Canal, Great Lakes waterways, St Lawrence Seaway are some of the most important Canals of North America. North America is rich in mineral resources such as iron ore, petroleum and natural gas, copper, gold, silver, nickel, sulphur, coal etc. The Prairie region of North America is ideally suited for the cultivation of wheat. ▸ The coniferous forests of the North America provides large quantities of soft wood. The prominent trees are fir, pine, larch and spruce etc. ▸ Lake Superior is the largest sweet water lake in the world. ▸ Maize, wheat and barley are the important cereals grown in North America. ▸ Canada is the largest producer of newsprint in the world. ▸ The Panama Canal connects Atlantic and Pacific ocean. By using Panama canal, the distance from New York to San Francisco can be shortened to nearly 23200 km.
It has 13 countries. Latitude 12° N and 55° N Longitude 35° W and 81° W Area 17820770 sq km (approx 12 %) Population 385742554 (5th) Highest Point Aconcagua (6960 m) Lowest Point Valdes Peninsula (-39.9 m) Straits Strait of Magellan Deserts Atacama and Patagonia ▸ South America has been divided into three physical divisions namely two Eastern highlands, the central plains, the Western mountains and the Western coastal strips. ▸ Cotopaxi in Ecuador is one of the highest active volcanoes in the world. ▸ Paraguay and Bolivia are the only landlocked countries. ▸ Pampas is the most fertile region of South America and Alfa-Alfa grasses are found here. ▸ It is the fourth largest continent and roughly triangular in shape. ▸ It is situated to the South of North America, mostly in Southern hemisphere. It is surrounded by Caribbean sea in the North, Atlantic ocean in the East, Antarctica ocean in the South and Pacific ocean in theWest. ▸ South America as well as Mexico, Central America and West Indies are collectively known as Latin America. Physical Aspects of South America
Western Mountains, Andes,Brazilian highlands and GuianaHighlands
Amazon, Magdalena, Orinico,Parana and La Plata
Maracaibo, Titicaca, Popo
Bolivian and Patagonia
Important Information of South America ▸ It contains the world's highest waterfall i.e. Angel falls in Venezuela on Orinoco river. ▸ It contains the world's 2nd longest river after Nile and the largest river by volume i.e. Amazon river. ▸ The longest mountain range of the world i.e. the Andes lies in South America. ▸ Moreover, the driest place on Earth i.e. Atacama desert, the largest rain forest i.e. the Amazon rain forest, the highest capital city i.e. Lapaz (Bolivia), the highest commercially navigable lake i.e. Lake Titicaca are situated in South America. ▸ Llanos and Campos are the Savanna grassland in South America. Selvas are the equatorial rainforests of Amazon basin. Some of the countries of South America are specialised in coffee plantation (Brazil, Ecuador, Columbia and Venezuela etc), maize cultivation and wheat cultivation. ▸ South America is rich in minerals such as petroleum, aluminium, bauxite, copper, gold, lead, nickel, nitrates, diamond coal etc. ▸ Brazil has the world's largest reserves of iron in Serra dos carajas hills. ▸ Brazil is also known as the coffee bowl of the world, because it is the largest producer of coffee. ▸ Brazil is the only country through which both equator and one of the tropics (Tropic of Capricorn) passes.
Latitude 35° N and 73° N Longitude 25° W and 65° E Area 10530750 sq km (approx) (7.1 %) Population 731000000 Ocean and Seas Atlantic Ocean, Arctic Ocean, Mediterranean Sea, Caspian Sea, Black Sea, White Sea, North Sea, Norwegian Sea, Baltic Sea, Gulf of Bothnia, Gulf of Finland, Bay of Biscay, Aegean Sea and Adriatic Sea. Highest Point Mt Elbrus (5642 m) Lowest Point Caspian Sea (-28.0 m) Straits Strait of Gibraltar Lakes Lake Ladoga, Onega, Peipus, Vanern, Vattern Islands British Isles, Iceland, Sardinia, Sicily, Crete ▸ Greenland, the world's largest island belongs to Denmark. Important Gulf and Bays
Gulf of Bothnia
Sweden and Finland
English Channel
Britain and France
Gulf of Lions
South of France
Bay of Biscay
France and Spain
▸ Wheat is the most important crop of Europe. The Ruhr in Germany is the biggest and richest coal field of Europe. Other coal fields in Germany are Saar and Saxony. ▸ It is the second smallest continent in the world, by area, after Australia. ▸ Europe is situated between Ural mountains in the East and Atlantic ocean in the West, in the West of Asia and North of Africa. ▸ To the North of Europe lies Arctic ocean, to the South lies the Mediterranean sea, the Black sea and the Caucasus mountain and to the East Ural mountains and the Caspian sea. ▸ Balkan States It is a group of 9 countries namely Serbia and Montenegro, Slovenia, Croatia, Bosnia Herzegovina, Macedonia, Bulgaria, Greece, Romania Albania and Kosovo. However, Montenegro became an independent state in 2006 and Kosovo in 2008. ▸ Baltic States It is a group of three countries namely Estonia, Lithuania and Latvia. Iceland, Norway, Sweden and Denmark are collectively called as Scandinavian countries. The world's most Northerly capital is Reykjavik. Physical Aspects of Europe
Vesuvius, Appennines, Vosges, Alps, Mt Etna, Dinaric Alps, Carpathian, Pindus, Ural, Caucasus, Black Forest, Mt Stromboli, Kjolen, Pennine, Cantabarian Pyrenees, Sierra Morena and Sierra Nevada
Po, Tiber, Rhine, Ebro, Garrone, Loire, Seine, Weser, Elbe, Wista, Onega, Dvina, Mezen, Volga, Don, Dnieper, Dneister and Danube, Rhine
Iberian, Balkan and Kola
Important Information of Europe ▸ Copenhagen, capital of Denmark is known as the key to the Baltic. ▸ Finland is known as the land of forests and lakes. ▸ Both intensive and extensive cultivation are done in Europe with a great variety of crops due to the occurrence of different kinds of soil and climate. On the steppes, wheat, sugar beet and sun flowers are the major crops, whereas in the Mediterranean region, fruit cultivation is prominent. Moreover, cattle, sheep and pigs are reared for meat, milk and its products. ▸ The continental shelf areas around Europe including Dogger Bank are rich in fish. ▸ Europe is rich in minerals such as iron ore, petroleum, coal, copper etc. ▸ United Kingdom is the name given to the combination of Great Britain and Northern Ireland. Great Britain consists of England, Scotland and Waves. ▸ UK is one of the most industrialized nations of the world, though it lacks the raw material. It is self sufficient in petrol. ▸ France is the third largest country in Europe. Russia is the largest country of the world and the highest populated country of Europe. ▸ Vatican city is in Rome, Italy. It is the smallest country of the world both in terms of area and population.
Australia is an inland continent. Latitude 10°41'S and 39°S Longitude 114°E and 154°E Area 7830682 sq km (5.3%) Population 24 million Highest Point Mt. Kosciusko (2228 m) in island of New Guinea Lowest Point Lake Eyre (– 15.8 m) ▸ Islands Tasmania. ▸ It is the smallest continent of the world. It lies entirely in the Southern hemisphere. The Tropic of Capricorn runs almost through the middle of the continent and divides the continent in two equal parts. ▸ It is the only continent that is also a country and it lies between Pacific and Indian ocean. It is surrounded by Timor sea in the North-West, Arafura sea and Gulf of Carpentaria in the North, Great Barrier Reef in the North-East and Great Australian Bight in the South. To the South-East of the mainland lies the mountainous island of Tasmania. Physical Aspects of Australia
Great Dividing range,Darling range, Musgrave, Flinders and Australian Alps
Gibson, Great Sandy, Great Victoria, Simpson, Little Sandy, Western desert, Rangipo and Tanami etc
Murray, Darling and Swan
Important Information of Australia ▸ Australia is known as Forgotten land. It was discovered by Captain Cook in 1770. Australia is the largest producer of bauxite. ▸ It is divided into six states. The six states are Western Australia, Northern Territory, Queensland, New South Wales, South Australia and Victoria. ▸ Largest city of Australia is Sydney. ▸ The highest peak of Australia is Mt Kosciusko (2228 m). ▸ Great Barrier reef is the world's longest coral Reef and is located in the North-East of Australia. The largest lake of Australia is Eyre. ▸ The first European to dicover New Zealand was Abel Tasman. ▸ The highest peak of New Zealand is Mt Cook (3724 m). ▸ Agriculture is carried out in the Murray Darling Basin, around the river Swan in Perth and along the rainy East coast. Wheat and sugarcane are important crops. Moreover, commercial farming is a big business in Australia. ▸ Coal, iron ore, bauxite, uranium, gold and petroleum are the major mineral resources of Australia. ▸ Being a dry country, forest do not occur in continuous belt, however tropical forests are found in the North coastal region, which gets monsoon rain. ▸ The Australian trade is based on agriculture, animal rearing and minerals.
▸ It was discovered in 1820. ▸ Ronald Amundsen was the first man to reach geographical South pole in Antarctica. ▸ It is called as the continent for science because it provides unique opportunity to scientists to learn about the world. ▸ Mt Erebus is the only active volcano on Antarctica. ▸ Mt Vinson (4897 m) is the highest peak of Antarctica. ▸ It is the only continent, which is completely frozen. It is, therefore, known as White Continent. Highest/Lowest Points of Various Continents Continent Highest (m) Lowest (m)
Mt Everest (8848)
Dead Sea (–396)
Mt Kilimanjaro (5951)
Lake Assal (–151)
Mt McKinley (6194)
Death Valley (–87)
Mt Aconcagua (6962)
Valdes Peninsula (–40)
Vinson Massif (4897)
Bentley Sub-glacial Trench (–2538)
Mt El' Brus (5642)
Caspian Sea (–28)
Kosciusko (2228)
Lake Eyre (–16)
Important Straits of the World
Bab-al- Mandeb
Red Sea and Arabian Sea
Arabia and Africa
Bering
Arctic Ocean and Bering Sea
Alaska and Asia
Bosphorus
Black Sea and Marmara Sea
Turkey
Dover
North Sea and Atlantic Ocean
England and Europe
Florida
Gulf of Mexico and Atlantic Ocean
Florida and Bahamas Islands
Gibralter
Mediterranean Sea and Atlantic Ocean
Spain and Africa
Malacca
Java Sea and Bay of Bengal
India and Indonesia
Palk
Bay of Bengal and Indian Ocean
India and Sri Lanka
Megellan
South Pacific and South Atlantic Ocean
Sunda
Java Sea and Indian Ocean
Important Canals of the World
Canal
Connects
Panama
Pacific Ocean with Caribbean Sea
Suez
Mediterranean Sea to Red Sea
Erie
Atlantic Ocean to Great Lakes
Kiel
North Sea to Baltic Sea
Oceans of the World (Area wise)
Ocean
Deepest Point
Mariana Trench
Puerto Rico Trench
Java Trench
Eurasian Basin
River Side Cities
Sittwe (Myanmar)
Irawady
Baghdad (Iraq)
Tigris
Basara (Iraq)
Tigris and Euphrates
Belgrade
Danube
Berlin (Germany)
Spree
Bristol (UK)
Avon
Budapest (Hungary)
Cairo (Egypt)
Nile
Canton
Si-Kiang
Glasgow (Scotland)
Clyde
Hamburg (Germany)
Elbe
Kabul
Karachi
Khartoum (Sudan)
Lahore
Lisbon (Portugal)
Tangus
London (UK)
Thames
Montreal (Canada)
Ottawa
Nanking
Yang-tse-Kiang
New Castle (UK)
Tyre
New Orleans (USA)
Mississippi
New York (USA)
Hudson
Paris (France)
Seine
Philadelphia (USA)
Delaware
Rome (Italy)
Tiber
Shanghai
Jhelum
Warsaw (Poland)
Vistula
Yangon (Myanmar)
Major Rivers of the World
Victoria Lake
Amazon
Andes (Peru)
Yangtze
Tibetan Kiang Plateau
Mississippi Missouri
Itaska Lake (USA)
Yenisei
Tannu-Ola Mountains
Huang Ho
Kunlun Mountains
Ob
Altai Mountains, Russia
Congo
Lualaba and Luapula rivers
Amur
North-East China
Lena
Baikal Mountains
Mekong
Tibetan Highlands
Niger
Guinea
Important Lakes of the World
Caspian
Superior
Canada and USA
Victoria
Huron
Michigan
Tanganyika
Baikal
Great Bear
Canada
Aral
Kazakhstan
Great Slave
List of Waterfalls
1 Angel Falls
Venezuela
2 Tugela Falls
3 Cataratas las Tres Hermanas
4 Olo'upena Falls
United Sates
5 Catarata Yumbilla
Major Islands of the World
1 Greenland
2130800
Denmark
2 New Guinea
785753
3 Borneo
748168
Indonesia and Malaysia
4 Madagascar
587713
5 Baffin Island
507451
6 Sumatra
443066
Minerals of the World
Mineral
Leading Producer
Platinum
Chromium
Vanadium
Antimony
Tungsten
Phosphate
Morocco
Iron ore
Mines of the World
Kimberley (South Africa)
Lumbabashi (Zaire)
Wankee (Zimbabwe)
Witwatersrand (South Africa)
Katanga (Zaire-Zambia)
Copper and Cobalt
Kasai Province (Zaire)
Bort Diamond
Agriculture
Agricultural Produce
Brazil
Liberia
Kenya
Oil Palm
Nigeria
Cocoa
Ghana
Coconut
Philippines
Date Palm
Maize
Wool
Sisal
Cloves
Industrial Cities
Anshan (China)
Iron and Steel
Baku (Azerbaijan)
Belfast (Ireland)
Ship building
Birmingham (UK)
Chicago (USA)
Meat packing
Detroit (USA)
Automobile
Havana (Cuba)
Cigars
Hollywood (USA)
Films
Johannesburg (South Africa)
Gold Mining
Kansas City (USA)
Kawasaki (Japan)
Diamond mining
Krivoi Rog (Ukraine)
Leeds (UK)
Woollen textiles
Leningrad (Russia)
Los Angeles (USA)
Lyon (France)
Silk textiles
Magnitogorsk (Russia)
Manchester (UK)
Cotton textile
Milan (Italy)
Silk textile
Multan (Pakistan)
Pottery
Munich (Germany)
Lenses
Nagoya (Japan)
Locomotives
Pittsburg (USA)
Plymouth (USA)
Rourkela (India)
Sheffield (UK)
Cutlery
Vladivostok (Russia)
Wellington (New Zealand)
Dairying
Arizona (USA)
Optics
Bhiwandi (India)
Power looms
Vijayawada (India)
Auto parts
Bhagalpur (India)
Changed Names of Cities, States and Countries
Abyssinia
Ethiopia
Angora
Ankara
Basutoland
Batavia
Jakarta
British Guiana
Guyana
Burma
Myanmar
Cape Canaveral
Cape Kennedy
Cawnpore
Central Provinces
Ceylon
Sri Lanka
Christina
Oslo
Constantinople
Istanbul
Dacca
Dhaka
Dutch East Indies
Dutch Guiana
Surinam
Gold Coast
Holland
The Netherlands
Ivory Coast
Cote D'Ivoire
Malagasy
Malaya
Mesopotamia
Iraq
Nippon
Northern Rhodesia
Zambia
Nyasaland
Malawi
Peking
Beijing
Persia
Petrograd
Leningrad
Quilon
Kollam
Rangoon
Yangon
Rhodesia
Zimbabwe
Saigon
Ho Chi Minh City
Sandwich Islands
Hawaiian Islands
Siam
South-West Africa
Namibia
Spanish Guinea
Equatorial Guinea
Zaire
Republic of Congo
Important International Boundary Lines
Durand Line (1896)
Pakistan and Afghanistan
Hindenburg Line
Germany and Poland
Maginot Line
France and Germany
Order Neisse Line
Siegfried Line
Fortification between Germany and France
38th Parallel Line
North and South Korea
49th Parallel Line
USA and Canada
24th Parallel Line
Pakistan claims that it is the boundary between India and Pakistan in Rann of Kutch
17th Parallel Line
North Vietnam and South Vietnam (presently not in use)
Famous Tribes of the World
Afridis
Tribes residing in the North-West Frontier (Pakistan)
Bantus
Negroes living in the Central and South Africa
Boers
The Dutch settlers of South Africa
Cossacks
People living in the Southern and Eastern Frontiers of Russia
Eskimos
Inhabitants of Greenland and of Arctic regions
Flemings
A term used for the People of Belgium
Hamites
Inhabitants of North-West Africa
Khirgiz
People living in Central Asia
Kurds
Tribes living in Kurdistan (Iraq)
Magyars
Inhabitants of Hungary
Maoris
Inhabitants of New Zealand
Negroesz
Mostly found in Africa
Pygmies
Short sized people found in Congo basin in Africa
RedIndians
Original inhabitants of North America
Semites
Caucasian people of ancient times
Zulus
People of South Africa living in certain part of Natal
▸ India is the 7th largest country in the world with an area of 3287263 sq km, which is 2.42% of world's area. ▸ India is the second most populous country in the world with a population of 1.21 billion (2011), which is 17.44% of the world. ▸ Indian sub-continent is located in the Northern and Eastern hemisphere. ▸ India shares longest boundary with Bangladesh (4096 km), followed by China (3488 km), Pakistan (3323 km), Nepal (1751 km), Myanmar (1643 km), Bhutan (699 km) and Afghanistan (106 km). ▸ In India, the Tropic of Cancer (23.5°N latitude) passes through 8 States (Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram). ▸ Islands Andaman and Nicobar Islands in the Bay of Bengal; Lakshadweep, Amindive and Minicoy in the Arabian Sea. ▸ Indian Standard Time (IST) The 82°30' E longitude is taken as the Standard Time Meridian of India, as it passes through middle of India (from Naini, near Allahabad). ▸ The 82° 30' E Meridian also dictates time in Sri Lanka and Nepal. ▸ In the South, on the Eastern side, the Gulf of Mannar and the Palk Strait separates India from Sri Lanka.
▸ Latitudinal extent 8°4' North to 37° 6' North ▸ Longitudinal extent 68°7' East to 97° 25' East ▸ North-South extent 3214 km ▸ East-West extent 2933 km ▸ Land Frontiers 15200 km ▸ Total Coastline 7516.6 km ▸ Number of States 29 ▸ Number of Union Territories 7 ▸ Land Neighbours (7) Pakistan, Afghanistan, China, Nepal, Bhutan, Bangladesh and Myanmar ▸ States with Longest Coastline Gujarat ▸ Active Volcano Barren Island in Andaman and Nicobar Islands ▸ Southern most point Indira Point or Pygmalion point in Great Nicobar ▸ Southern most tip of mainland Kanyakumari ▸ Northern most point Indira Col ▸ Western most point West of Ghaur Mota in Gujarat ▸ Eastern most point Kibithu in Arunachal Pradesh Indian States Situated on the Border
Pakistan (4)
Gujarat, Rajasthan, Punjab and Jammu and Kashmir
Afghanistan (1)
China (5)
Jammu and Kashmir, Uttarakhand, Himachal Pradesh, Sikkim and Arunachal Pradesh
Nepal (5)
Uttar Pradesh, Uttarakhand, Bihar, West Bengal, Sikkim
Bhutan (4)
Sikkim, West Bengal, Assam and Arunachal Pradesh
Bangladesh (5)
West Bengal, Assam, Meghalaya, Tripura and Mizoram
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